Split out main module

src/knowledge_search_mcp/__init__.py

@@ -0,0 +1,15 @@
+"""MCP server for semantic search over Vertex AI Vector Search."""
+
+from .clients.storage import GoogleCloudFileStorage
+from .clients.vector_search import GoogleCloudVectorSearch
+from .models import AppContext, SearchResult, SourceNamespace
+from .utils.cache import LRUCache
+
+__all__ = [
+    "GoogleCloudFileStorage",
+    "GoogleCloudVectorSearch",
+    "SourceNamespace",
+    "SearchResult",
+    "AppContext",
+    "LRUCache",
+]

src/knowledge_search_mcp/clients/__init__.py

@@ -0,0 +1,11 @@
+"""Client modules for Google Cloud services."""
+
+from .base import BaseGoogleCloudClient
+from .storage import GoogleCloudFileStorage
+from .vector_search import GoogleCloudVectorSearch
+
+__all__ = [
+    "BaseGoogleCloudClient",
+    "GoogleCloudFileStorage",
+    "GoogleCloudVectorSearch",
+]

src/knowledge_search_mcp/clients/base.py

@@ -0,0 +1,31 @@
+# ruff: noqa: INP001
+"""Base client with shared aiohttp session management."""
+
+import aiohttp
+
+
+class BaseGoogleCloudClient:
+    """Base class with shared aiohttp session management."""
+
+    def __init__(self) -> None:
+        """Initialize session tracking."""
+        self._aio_session: aiohttp.ClientSession | None = None
+
+    def _get_aio_session(self) -> aiohttp.ClientSession:
+        """Get or create aiohttp session with connection pooling."""
+        if self._aio_session is None or self._aio_session.closed:
+            connector = aiohttp.TCPConnector(
+                limit=300,
+                limit_per_host=50,
+            )
+            timeout = aiohttp.ClientTimeout(total=60)
+            self._aio_session = aiohttp.ClientSession(
+                timeout=timeout,
+                connector=connector,
+            )
+        return self._aio_session
+
+    async def close(self) -> None:
+        """Close aiohttp session if open."""
+        if self._aio_session and not self._aio_session.closed:
+            await self._aio_session.close()

src/knowledge_search_mcp/clients/storage.py

@@ -0,0 +1,144 @@
+# ruff: noqa: INP001
+"""Google Cloud Storage client with caching."""
+
+import asyncio
+import io
+from typing import BinaryIO
+
+import aiohttp
+from gcloud.aio.storage import Storage
+
+from ..logging import log_structured_entry
+from ..utils.cache import LRUCache
+from .base import BaseGoogleCloudClient
+
+HTTP_TOO_MANY_REQUESTS = 429
+HTTP_SERVER_ERROR = 500
+
+
+class GoogleCloudFileStorage(BaseGoogleCloudClient):
+    """Cache-aware helper for downloading files from Google Cloud Storage."""
+
+    def __init__(self, bucket: str, cache_size: int = 100) -> None:
+        """Initialize the storage helper with LRU cache."""
+        super().__init__()
+        self.bucket_name = bucket
+        self._aio_storage: Storage | None = None
+        self._cache = LRUCache(max_size=cache_size)
+
+    def _get_aio_storage(self) -> Storage:
+        if self._aio_storage is None:
+            self._aio_storage = Storage(
+                session=self._get_aio_session(),
+            )
+        return self._aio_storage
+
+    async def async_get_file_stream(
+        self,
+        file_name: str,
+        max_retries: int = 3,
+    ) -> BinaryIO:
+        """Get a file asynchronously with retry on transient errors.
+
+        Args:
+            file_name: The blob name to retrieve.
+            max_retries: Maximum number of retry attempts.
+
+        Returns:
+            A BytesIO stream with the file contents.
+
+        Raises:
+            TimeoutError: If all retry attempts fail.
+
+        """
+        cached_content = self._cache.get(file_name)
+        if cached_content is not None:
+            log_structured_entry(
+                "File retrieved from cache",
+                "INFO",
+                {"file": file_name, "bucket": self.bucket_name}
+            )
+            file_stream = io.BytesIO(cached_content)
+            file_stream.name = file_name
+            return file_stream
+
+        log_structured_entry(
+            "Starting file download from GCS",
+            "INFO",
+            {"file": file_name, "bucket": self.bucket_name}
+        )
+
+        storage_client = self._get_aio_storage()
+        last_exception: Exception | None = None
+
+        for attempt in range(max_retries):
+            try:
+                content = await storage_client.download(
+                    self.bucket_name,
+                    file_name,
+                )
+                self._cache.put(file_name, content)
+                file_stream = io.BytesIO(content)
+                file_stream.name = file_name
+                log_structured_entry(
+                    "File downloaded successfully",
+                    "INFO",
+                    {
+                        "file": file_name,
+                        "bucket": self.bucket_name,
+                        "size_bytes": len(content),
+                        "attempt": attempt + 1
+                    }
+                )
+            except TimeoutError as exc:
+                last_exception = exc
+                log_structured_entry(
+                    f"Timeout downloading gs://{self.bucket_name}/{file_name} (attempt {attempt + 1}/{max_retries})",
+                    "WARNING",
+                    {"error": str(exc)}
+                )
+            except aiohttp.ClientResponseError as exc:
+                last_exception = exc
+                if (
+                    exc.status == HTTP_TOO_MANY_REQUESTS
+                    or exc.status >= HTTP_SERVER_ERROR
+                ):
+                     log_structured_entry(
+                        f"HTTP {exc.status} downloading gs://{self.bucket_name}/{file_name} (attempt {attempt + 1}/{max_retries})",
+                        "WARNING",
+                        {"status": exc.status, "message": str(exc)}
+                    )
+                else:
+                    log_structured_entry(
+                        f"Non-retryable HTTP error downloading gs://{self.bucket_name}/{file_name}",
+                        "ERROR",
+                        {"status": exc.status, "message": str(exc)}
+                    )
+                    raise
+            else:
+                return file_stream
+
+            if attempt < max_retries - 1:
+                delay = 0.5 * (2**attempt)
+                log_structured_entry(
+                    "Retrying file download",
+                    "INFO",
+                    {"file": file_name, "delay_seconds": delay}
+                )
+                await asyncio.sleep(delay)
+
+        msg = (
+            f"Failed to download gs://{self.bucket_name}/{file_name} "
+            f"after {max_retries} attempts"
+        )
+        log_structured_entry(
+            "File download failed after all retries",
+            "ERROR",
+            {
+                "file": file_name,
+                "bucket": self.bucket_name,
+                "max_retries": max_retries,
+                "last_error": str(last_exception)
+            }
+        )
+        raise TimeoutError(msg) from last_exception

src/knowledge_search_mcp/clients/vector_search.py

@@ -0,0 +1,226 @@
+# ruff: noqa: INP001
+"""Google Cloud Vector Search client."""
+
+import asyncio
+from collections.abc import Sequence
+
+from gcloud.aio.auth import Token
+
+from ..logging import log_structured_entry
+from ..models import SearchResult, SourceNamespace
+from .base import BaseGoogleCloudClient
+from .storage import GoogleCloudFileStorage
+
+
+class GoogleCloudVectorSearch(BaseGoogleCloudClient):
+    """Minimal async client for the Vertex AI Matching Engine REST API."""
+
+    def __init__(
+        self,
+        project_id: str,
+        location: str,
+        bucket: str,
+        index_name: str | None = None,
+    ) -> None:
+        """Store configuration used to issue Matching Engine queries."""
+        super().__init__()
+        self.project_id = project_id
+        self.location = location
+        self.storage = GoogleCloudFileStorage(bucket=bucket)
+        self.index_name = index_name
+        self._async_token: Token | None = None
+        self._endpoint_domain: str | None = None
+        self._endpoint_name: str | None = None
+
+    async def _async_get_auth_headers(self) -> dict[str, str]:
+        if self._async_token is None:
+            self._async_token = Token(
+                session=self._get_aio_session(),
+                scopes=[
+                    "https://www.googleapis.com/auth/cloud-platform",
+                ],
+            )
+        access_token = await self._async_token.get()
+        return {
+            "Authorization": f"Bearer {access_token}",
+            "Content-Type": "application/json",
+        }
+
+    async def close(self) -> None:
+        """Close aiohttp sessions for both vector search and storage."""
+        await super().close()
+        await self.storage.close()
+
+    def configure_index_endpoint(
+        self,
+        *,
+        name: str,
+        public_domain: str,
+    ) -> None:
+        """Persist the metadata needed to access a deployed endpoint."""
+        if not name:
+            msg = "Index endpoint name must be a non-empty string."
+            raise ValueError(msg)
+        if not public_domain:
+            msg = "Index endpoint domain must be a non-empty public domain."
+            raise ValueError(msg)
+        self._endpoint_name = name
+        self._endpoint_domain = public_domain
+
+    async def async_run_query(
+        self,
+        deployed_index_id: str,
+        query: Sequence[float],
+        limit: int,
+        source: SourceNamespace | None = None,
+    ) -> list[SearchResult]:
+        """Run an async similarity search via the REST API.
+
+        Args:
+            deployed_index_id: The ID of the deployed index.
+            query: The embedding vector for the search query.
+            limit: Maximum number of nearest neighbors to return.
+            source: Optional namespace filter to restrict results by source.
+
+        Returns:
+            A list of matched items with id, distance, and content.
+
+        """
+        if self._endpoint_domain is None or self._endpoint_name is None:
+            msg = (
+                "Missing endpoint metadata. Call "
+                "`configure_index_endpoint` before querying."
+            )
+            log_structured_entry(
+                "Vector search query failed - endpoint not configured",
+                "ERROR",
+                {"error": msg}
+            )
+            raise RuntimeError(msg)
+
+        domain = self._endpoint_domain
+        endpoint_id = self._endpoint_name.split("/")[-1]
+        url = (
+            f"https://{domain}/v1/projects/{self.project_id}"
+            f"/locations/{self.location}"
+            f"/indexEndpoints/{endpoint_id}:findNeighbors"
+        )
+
+        log_structured_entry(
+            "Starting vector search query",
+            "INFO",
+            {
+                "deployed_index_id": deployed_index_id,
+                "neighbor_count": limit,
+                "endpoint_id": endpoint_id,
+                "embedding_dimension": len(query)
+            }
+        )
+
+        datapoint: dict = {"feature_vector": list(query)}
+        if source is not None:
+            datapoint["restricts"] = [
+                {"namespace": "source", "allow_list": [source.value]},
+            ]
+        payload = {
+            "deployed_index_id": deployed_index_id,
+            "queries": [
+                {
+                    "datapoint": datapoint,
+                    "neighbor_count": limit,
+                },
+            ],
+        }
+
+        try:
+            headers = await self._async_get_auth_headers()
+            session = self._get_aio_session()
+            async with session.post(
+                url,
+                json=payload,
+                headers=headers,
+            ) as response:
+                if not response.ok:
+                    body = await response.text()
+                    msg = f"findNeighbors returned {response.status}: {body}"
+                    log_structured_entry(
+                        "Vector search API request failed",
+                        "ERROR",
+                        {
+                            "status": response.status,
+                            "response_body": body,
+                            "deployed_index_id": deployed_index_id
+                        }
+                    )
+                    raise RuntimeError(msg)
+                data = await response.json()
+
+            neighbors = data.get("nearestNeighbors", [{}])[0].get("neighbors", [])
+            log_structured_entry(
+                "Vector search API request successful",
+                "INFO",
+                {
+                    "neighbors_found": len(neighbors),
+                    "deployed_index_id": deployed_index_id
+                }
+            )
+
+            if not neighbors:
+                log_structured_entry(
+                    "No neighbors found in vector search",
+                    "WARNING",
+                    {"deployed_index_id": deployed_index_id}
+                )
+                return []
+
+            # Fetch content for all neighbors
+            content_tasks = []
+            for neighbor in neighbors:
+                datapoint_id = neighbor["datapoint"]["datapointId"]
+                file_path = f"{self.index_name}/contents/{datapoint_id}.md"
+                content_tasks.append(
+                    self.storage.async_get_file_stream(file_path),
+                )
+
+            log_structured_entry(
+                "Fetching content for search results",
+                "INFO",
+                {"file_count": len(content_tasks)}
+            )
+
+            file_streams = await asyncio.gather(*content_tasks)
+            results: list[SearchResult] = []
+            for neighbor, stream in zip(
+                neighbors,
+                file_streams,
+                strict=True,
+            ):
+                results.append(
+                    SearchResult(
+                        id=neighbor["datapoint"]["datapointId"],
+                        distance=neighbor["distance"],
+                        content=stream.read().decode("utf-8"),
+                    ),
+                )
+
+            log_structured_entry(
+                "Vector search completed successfully",
+                "INFO",
+                {
+                    "results_count": len(results),
+                    "deployed_index_id": deployed_index_id
+                }
+            )
+            return results
+
+        except Exception as e:
+            log_structured_entry(
+                "Vector search query failed with exception",
+                "ERROR",
+                {
+                    "error": str(e),
+                    "error_type": type(e).__name__,
+                    "deployed_index_id": deployed_index_id
+                }
+            )
+            raise

src/knowledge_search_mcp/main.py

@@ -1,729 +1,15 @@
 # ruff: noqa: INP001
-"""Async helpers for querying Vertex AI vector search via MCP."""
+"""MCP server for semantic search over Vertex AI Vector Search."""
 
-import asyncio
-import io
 import time
-from collections import OrderedDict
-from collections.abc import AsyncIterator, Sequence
-from contextlib import asynccontextmanager
-from dataclasses import dataclass
-from enum import Enum
-from typing import BinaryIO, TypedDict
 
-import aiohttp
-from gcloud.aio.auth import Token
-from gcloud.aio.storage import Storage
-from google import genai
-from google.genai import types as genai_types
 from mcp.server.fastmcp import Context, FastMCP
 
-from .config import Settings, _args, cfg
+from .config import _args
 from .logging import log_structured_entry
-
+from .models import AppContext, SourceNamespace
-HTTP_TOO_MANY_REQUESTS = 429
+from .server import lifespan
-HTTP_SERVER_ERROR = 500
+from .services.search import filter_search_results, format_search_results, generate_query_embedding
-
-
-class LRUCache:
-    """Simple LRU cache with size limit."""
-
-    def __init__(self, max_size: int = 100) -> None:
-        """Initialize cache with maximum size."""
-        self.cache: OrderedDict[str, bytes] = OrderedDict()
-        self.max_size = max_size
-
-    def get(self, key: str) -> bytes | None:
-        """Get item from cache, returning None if not found."""
-        if key not in self.cache:
-            return None
-        # Move to end to mark as recently used
-        self.cache.move_to_end(key)
-        return self.cache[key]
-
-    def put(self, key: str, value: bytes) -> None:
-        """Put item in cache, evicting oldest if at capacity."""
-        if key in self.cache:
-            self.cache.move_to_end(key)
-        self.cache[key] = value
-        if len(self.cache) > self.max_size:
-            self.cache.popitem(last=False)
-
-    def __contains__(self, key: str) -> bool:
-        """Check if key exists in cache."""
-        return key in self.cache
-
-
-class BaseGoogleCloudClient:
-    """Base class with shared aiohttp session management."""
-
-    def __init__(self) -> None:
-        """Initialize session tracking."""
-        self._aio_session: aiohttp.ClientSession | None = None
-
-    def _get_aio_session(self) -> aiohttp.ClientSession:
-        """Get or create aiohttp session with connection pooling."""
-        if self._aio_session is None or self._aio_session.closed:
-            connector = aiohttp.TCPConnector(
-                limit=300,
-                limit_per_host=50,
-            )
-            timeout = aiohttp.ClientTimeout(total=60)
-            self._aio_session = aiohttp.ClientSession(
-                timeout=timeout,
-                connector=connector,
-            )
-        return self._aio_session
-
-    async def close(self) -> None:
-        """Close aiohttp session if open."""
-        if self._aio_session and not self._aio_session.closed:
-            await self._aio_session.close()
-
-
-class SourceNamespace(str, Enum):
-    """Allowed values for the 'source' namespace filter."""
-
-    EDUCACION_FINANCIERA = "Educacion Financiera"
-    PRODUCTOS_Y_SERVICIOS = "Productos y Servicios"
-    FUNCIONALIDADES_APP_MOVIL = "Funcionalidades de la App Movil"
-
-
-class GoogleCloudFileStorage(BaseGoogleCloudClient):
-    """Cache-aware helper for downloading files from Google Cloud Storage."""
-
-    def __init__(self, bucket: str, cache_size: int = 100) -> None:
-        """Initialize the storage helper with LRU cache."""
-        super().__init__()
-        self.bucket_name = bucket
-        self._aio_storage: Storage | None = None
-        self._cache = LRUCache(max_size=cache_size)
-
-    def _get_aio_storage(self) -> Storage:
-        if self._aio_storage is None:
-            self._aio_storage = Storage(
-                session=self._get_aio_session(),
-            )
-        return self._aio_storage
-
-    async def async_get_file_stream(
-        self,
-        file_name: str,
-        max_retries: int = 3,
-    ) -> BinaryIO:
-        """Get a file asynchronously with retry on transient errors.
-
-        Args:
-            file_name: The blob name to retrieve.
-            max_retries: Maximum number of retry attempts.
-
-        Returns:
-            A BytesIO stream with the file contents.
-
-        Raises:
-            TimeoutError: If all retry attempts fail.
-
-        """
-        cached_content = self._cache.get(file_name)
-        if cached_content is not None:
-            log_structured_entry(
-                "File retrieved from cache",
-                "INFO",
-                {"file": file_name, "bucket": self.bucket_name}
-            )
-            file_stream = io.BytesIO(cached_content)
-            file_stream.name = file_name
-            return file_stream
-
-        log_structured_entry(
-            "Starting file download from GCS",
-            "INFO",
-            {"file": file_name, "bucket": self.bucket_name}
-        )
-
-        storage_client = self._get_aio_storage()
-        last_exception: Exception | None = None
-
-        for attempt in range(max_retries):
-            try:
-                content = await storage_client.download(
-                    self.bucket_name,
-                    file_name,
-                )
-                self._cache.put(file_name, content)
-                file_stream = io.BytesIO(content)
-                file_stream.name = file_name
-                log_structured_entry(
-                    "File downloaded successfully",
-                    "INFO",
-                    {
-                        "file": file_name,
-                        "bucket": self.bucket_name,
-                        "size_bytes": len(content),
-                        "attempt": attempt + 1
-                    }
-                )
-            except TimeoutError as exc:
-                last_exception = exc
-                log_structured_entry(
-                    f"Timeout downloading gs://{self.bucket_name}/{file_name} (attempt {attempt + 1}/{max_retries})",
-                    "WARNING",
-                    {"error": str(exc)}
-                )
-            except aiohttp.ClientResponseError as exc:
-                last_exception = exc
-                if (
-                    exc.status == HTTP_TOO_MANY_REQUESTS
-                    or exc.status >= HTTP_SERVER_ERROR
-                ):
-                     log_structured_entry(
-                        f"HTTP {exc.status} downloading gs://{self.bucket_name}/{file_name} (attempt {attempt + 1}/{max_retries})",
-                        "WARNING",
-                        {"status": exc.status, "message": str(exc)}
-                    )
-                else:
-                    log_structured_entry(
-                        f"Non-retryable HTTP error downloading gs://{self.bucket_name}/{file_name}",
-                        "ERROR",
-                        {"status": exc.status, "message": str(exc)}
-                    )
-                    raise
-            else:
-                return file_stream
-
-            if attempt < max_retries - 1:
-                delay = 0.5 * (2**attempt)
-                log_structured_entry(
-                    "Retrying file download",
-                    "INFO",
-                    {"file": file_name, "delay_seconds": delay}
-                )
-                await asyncio.sleep(delay)
-
-        msg = (
-            f"Failed to download gs://{self.bucket_name}/{file_name} "
-            f"after {max_retries} attempts"
-        )
-        log_structured_entry(
-            "File download failed after all retries",
-            "ERROR",
-            {
-                "file": file_name,
-                "bucket": self.bucket_name,
-                "max_retries": max_retries,
-                "last_error": str(last_exception)
-            }
-        )
-        raise TimeoutError(msg) from last_exception
-
-
-class SearchResult(TypedDict):
-    """Structured response item returned by the vector search API."""
-
-    id: str
-    distance: float
-    content: str
-
-
-class GoogleCloudVectorSearch(BaseGoogleCloudClient):
-    """Minimal async client for the Vertex AI Matching Engine REST API."""
-
-    def __init__(
-        self,
-        project_id: str,
-        location: str,
-        bucket: str,
-        index_name: str | None = None,
-    ) -> None:
-        """Store configuration used to issue Matching Engine queries."""
-        super().__init__()
-        self.project_id = project_id
-        self.location = location
-        self.storage = GoogleCloudFileStorage(bucket=bucket)
-        self.index_name = index_name
-        self._async_token: Token | None = None
-        self._endpoint_domain: str | None = None
-        self._endpoint_name: str | None = None
-
-    async def _async_get_auth_headers(self) -> dict[str, str]:
-        if self._async_token is None:
-            self._async_token = Token(
-                session=self._get_aio_session(),
-                scopes=[
-                    "https://www.googleapis.com/auth/cloud-platform",
-                ],
-            )
-        access_token = await self._async_token.get()
-        return {
-            "Authorization": f"Bearer {access_token}",
-            "Content-Type": "application/json",
-        }
-
-    async def close(self) -> None:
-        """Close aiohttp sessions for both vector search and storage."""
-        await super().close()
-        await self.storage.close()
-
-    def configure_index_endpoint(
-        self,
-        *,
-        name: str,
-        public_domain: str,
-    ) -> None:
-        """Persist the metadata needed to access a deployed endpoint."""
-        if not name:
-            msg = "Index endpoint name must be a non-empty string."
-            raise ValueError(msg)
-        if not public_domain:
-            msg = "Index endpoint domain must be a non-empty public domain."
-            raise ValueError(msg)
-        self._endpoint_name = name
-        self._endpoint_domain = public_domain
-
-    async def async_run_query(
-        self,
-        deployed_index_id: str,
-        query: Sequence[float],
-        limit: int,
-        source: SourceNamespace | None = None,
-    ) -> list[SearchResult]:
-        """Run an async similarity search via the REST API.
-
-        Args:
-            deployed_index_id: The ID of the deployed index.
-            query: The embedding vector for the search query.
-            limit: Maximum number of nearest neighbors to return.
-            source: Optional namespace filter to restrict results by source.
-
-        Returns:
-            A list of matched items with id, distance, and content.
-
-        """
-        if self._endpoint_domain is None or self._endpoint_name is None:
-            msg = (
-                "Missing endpoint metadata. Call "
-                "`configure_index_endpoint` before querying."
-            )
-            log_structured_entry(
-                "Vector search query failed - endpoint not configured",
-                "ERROR",
-                {"error": msg}
-            )
-            raise RuntimeError(msg)
-
-        domain = self._endpoint_domain
-        endpoint_id = self._endpoint_name.split("/")[-1]
-        url = (
-            f"https://{domain}/v1/projects/{self.project_id}"
-            f"/locations/{self.location}"
-            f"/indexEndpoints/{endpoint_id}:findNeighbors"
-        )
-
-        log_structured_entry(
-            "Starting vector search query",
-            "INFO",
-            {
-                "deployed_index_id": deployed_index_id,
-                "neighbor_count": limit,
-                "endpoint_id": endpoint_id,
-                "embedding_dimension": len(query)
-            }
-        )
-
-        datapoint: dict = {"feature_vector": list(query)}
-        if source is not None:
-            datapoint["restricts"] = [
-                {"namespace": "source", "allow_list": [source.value]},
-            ]
-        payload = {
-            "deployed_index_id": deployed_index_id,
-            "queries": [
-                {
-                    "datapoint": datapoint,
-                    "neighbor_count": limit,
-                },
-            ],
-        }
-
-        try:
-            headers = await self._async_get_auth_headers()
-            session = self._get_aio_session()
-            async with session.post(
-                url,
-                json=payload,
-                headers=headers,
-            ) as response:
-                if not response.ok:
-                    body = await response.text()
-                    msg = f"findNeighbors returned {response.status}: {body}"
-                    log_structured_entry(
-                        "Vector search API request failed",
-                        "ERROR",
-                        {
-                            "status": response.status,
-                            "response_body": body,
-                            "deployed_index_id": deployed_index_id
-                        }
-                    )
-                    raise RuntimeError(msg)
-                data = await response.json()
-
-            neighbors = data.get("nearestNeighbors", [{}])[0].get("neighbors", [])
-            log_structured_entry(
-                "Vector search API request successful",
-                "INFO",
-                {
-                    "neighbors_found": len(neighbors),
-                    "deployed_index_id": deployed_index_id
-                }
-            )
-
-            if not neighbors:
-                log_structured_entry(
-                    "No neighbors found in vector search",
-                    "WARNING",
-                    {"deployed_index_id": deployed_index_id}
-                )
-                return []
-
-            # Fetch content for all neighbors
-            content_tasks = []
-            for neighbor in neighbors:
-                datapoint_id = neighbor["datapoint"]["datapointId"]
-                file_path = f"{self.index_name}/contents/{datapoint_id}.md"
-                content_tasks.append(
-                    self.storage.async_get_file_stream(file_path),
-                )
-
-            log_structured_entry(
-                "Fetching content for search results",
-                "INFO",
-                {"file_count": len(content_tasks)}
-            )
-
-            file_streams = await asyncio.gather(*content_tasks)
-            results: list[SearchResult] = []
-            for neighbor, stream in zip(
-                neighbors,
-                file_streams,
-                strict=True,
-            ):
-                results.append(
-                    SearchResult(
-                        id=neighbor["datapoint"]["datapointId"],
-                        distance=neighbor["distance"],
-                        content=stream.read().decode("utf-8"),
-                    ),
-                )
-
-            log_structured_entry(
-                "Vector search completed successfully",
-                "INFO",
-                {
-                    "results_count": len(results),
-                    "deployed_index_id": deployed_index_id
-                }
-            )
-            return results
-
-        except Exception as e:
-            log_structured_entry(
-                "Vector search query failed with exception",
-                "ERROR",
-                {
-                    "error": str(e),
-                    "error_type": type(e).__name__,
-                    "deployed_index_id": deployed_index_id
-                }
-            )
-            raise
-
-
-# ---------------------------------------------------------------------------
-# MCP Server
-# ---------------------------------------------------------------------------
-
-
-@dataclass
-class AppContext:
-    """Shared resources initialised once at server startup."""
-
-    vector_search: GoogleCloudVectorSearch
-    genai_client: genai.Client
-    settings: Settings
-
-
-async def _validate_genai_access(genai_client: genai.Client, cfg: Settings) -> str | None:
-    """Validate GenAI embedding access.
-
-    Returns:
-        Error message if validation fails, None if successful.
-    """
-    log_structured_entry("Validating GenAI embedding access", "INFO")
-    try:
-        test_response = await genai_client.aio.models.embed_content(
-            model=cfg.embedding_model,
-            contents="test",
-            config=genai_types.EmbedContentConfig(
-                task_type="RETRIEVAL_QUERY",
-            ),
-        )
-        if test_response and test_response.embeddings:
-            embedding_values = test_response.embeddings[0].values
-            log_structured_entry(
-                "GenAI embedding validation successful",
-                "INFO",
-                {"embedding_dimension": len(embedding_values) if embedding_values else 0}
-            )
-            return None
-        else:
-            msg = "Embedding validation returned empty response"
-            log_structured_entry(msg, "WARNING")
-            return msg
-    except Exception as e:
-        log_structured_entry(
-            "Failed to validate GenAI embedding access - service may not work correctly",
-            "WARNING",
-            {"error": str(e), "error_type": type(e).__name__}
-        )
-        return f"GenAI: {str(e)}"
-
-
-async def _validate_gcs_access(vs: GoogleCloudVectorSearch, cfg: Settings) -> str | None:
-    """Validate GCS bucket access.
-
-    Returns:
-        Error message if validation fails, None if successful.
-    """
-    log_structured_entry(
-        "Validating GCS bucket access",
-        "INFO",
-        {"bucket": cfg.bucket}
-    )
-    try:
-        session = vs.storage._get_aio_session()
-        token_obj = Token(
-            session=session,
-            scopes=["https://www.googleapis.com/auth/cloud-platform"],
-        )
-        access_token = await token_obj.get()
-        headers = {"Authorization": f"Bearer {access_token}"}
-
-        async with session.get(
-            f"https://storage.googleapis.com/storage/v1/b/{cfg.bucket}/o?maxResults=1",
-            headers=headers,
-        ) as response:
-            if response.status == 403:
-                msg = f"Access denied to bucket '{cfg.bucket}'. Check permissions."
-                log_structured_entry(
-                    "GCS bucket validation failed - access denied - service may not work correctly",
-                    "WARNING",
-                    {"bucket": cfg.bucket, "status": response.status}
-                )
-                return msg
-            elif response.status == 404:
-                msg = f"Bucket '{cfg.bucket}' not found. Check bucket name and project."
-                log_structured_entry(
-                    "GCS bucket validation failed - not found - service may not work correctly",
-                    "WARNING",
-                    {"bucket": cfg.bucket, "status": response.status}
-                )
-                return msg
-            elif not response.ok:
-                body = await response.text()
-                msg = f"Failed to access bucket '{cfg.bucket}': {response.status}"
-                log_structured_entry(
-                    "GCS bucket validation failed - service may not work correctly",
-                    "WARNING",
-                    {"bucket": cfg.bucket, "status": response.status, "response": body}
-                )
-                return msg
-            else:
-                log_structured_entry(
-                    "GCS bucket validation successful",
-                    "INFO",
-                    {"bucket": cfg.bucket}
-                )
-                return None
-    except Exception as e:
-        log_structured_entry(
-            "Failed to validate GCS bucket access - service may not work correctly",
-            "WARNING",
-            {"error": str(e), "error_type": type(e).__name__, "bucket": cfg.bucket}
-        )
-        return f"GCS: {str(e)}"
-
-
-async def _validate_vector_search_access(vs: GoogleCloudVectorSearch, cfg: Settings) -> str | None:
-    """Validate vector search endpoint access.
-
-    Returns:
-        Error message if validation fails, None if successful.
-    """
-    log_structured_entry(
-        "Validating vector search endpoint access",
-        "INFO",
-        {"endpoint_name": cfg.endpoint_name}
-    )
-    try:
-        headers = await vs._async_get_auth_headers()
-        session = vs._get_aio_session()
-        endpoint_url = (
-            f"https://{cfg.location}-aiplatform.googleapis.com/v1/{cfg.endpoint_name}"
-        )
-
-        async with session.get(endpoint_url, headers=headers) as response:
-            if response.status == 403:
-                msg = f"Access denied to endpoint '{cfg.endpoint_name}'. Check permissions."
-                log_structured_entry(
-                    "Vector search endpoint validation failed - access denied - service may not work correctly",
-                    "WARNING",
-                    {"endpoint": cfg.endpoint_name, "status": response.status}
-                )
-                return msg
-            elif response.status == 404:
-                msg = f"Endpoint '{cfg.endpoint_name}' not found. Check endpoint name and project."
-                log_structured_entry(
-                    "Vector search endpoint validation failed - not found - service may not work correctly",
-                    "WARNING",
-                    {"endpoint": cfg.endpoint_name, "status": response.status}
-                )
-                return msg
-            elif not response.ok:
-                body = await response.text()
-                msg = f"Failed to access endpoint '{cfg.endpoint_name}': {response.status}"
-                log_structured_entry(
-                    "Vector search endpoint validation failed - service may not work correctly",
-                    "WARNING",
-                    {"endpoint": cfg.endpoint_name, "status": response.status, "response": body}
-                )
-                return msg
-            else:
-                log_structured_entry(
-                    "Vector search endpoint validation successful",
-                    "INFO",
-                    {"endpoint": cfg.endpoint_name}
-                )
-                return None
-    except Exception as e:
-        log_structured_entry(
-            "Failed to validate vector search endpoint access - service may not work correctly",
-            "WARNING",
-            {"error": str(e), "error_type": type(e).__name__, "endpoint": cfg.endpoint_name}
-        )
-        return f"Vector Search: {str(e)}"
-
-
-@asynccontextmanager
-async def lifespan(_server: FastMCP) -> AsyncIterator[AppContext]:
-    """Create and configure the vector-search client for the server lifetime."""
-    log_structured_entry(
-        "Initializing MCP server",
-        "INFO",
-        {
-            "project_id": cfg.project_id,
-            "location": cfg.location,
-            "bucket": cfg.bucket,
-            "index_name": cfg.index_name,
-        }
-    )
-
-    vs: GoogleCloudVectorSearch | None = None
-    try:
-        # Initialize vector search client
-        log_structured_entry("Creating GoogleCloudVectorSearch client", "INFO")
-        vs = GoogleCloudVectorSearch(
-            project_id=cfg.project_id,
-            location=cfg.location,
-            bucket=cfg.bucket,
-            index_name=cfg.index_name,
-        )
-
-        # Configure endpoint
-        log_structured_entry(
-            "Configuring index endpoint",
-            "INFO",
-            {
-                "endpoint_name": cfg.endpoint_name,
-                "endpoint_domain": cfg.endpoint_domain,
-            }
-        )
-        vs.configure_index_endpoint(
-            name=cfg.endpoint_name,
-            public_domain=cfg.endpoint_domain,
-        )
-
-        # Initialize GenAI client
-        log_structured_entry(
-            "Creating GenAI client",
-            "INFO",
-            {"project_id": cfg.project_id, "location": cfg.location}
-        )
-        genai_client = genai.Client(
-            vertexai=True,
-            project=cfg.project_id,
-            location=cfg.location,
-        )
-
-        # Validate credentials and configuration by testing actual resources
-        # These validations are non-blocking - errors are logged but won't stop startup
-        log_structured_entry("Starting validation of credentials and resources", "INFO")
-
-        validation_errors = []
-
-        # Run all validations
-        genai_error = await _validate_genai_access(genai_client, cfg)
-        if genai_error:
-            validation_errors.append(genai_error)
-
-        gcs_error = await _validate_gcs_access(vs, cfg)
-        if gcs_error:
-            validation_errors.append(gcs_error)
-
-        vs_error = await _validate_vector_search_access(vs, cfg)
-        if vs_error:
-            validation_errors.append(vs_error)
-
-        # Summary of validations
-        if validation_errors:
-            log_structured_entry(
-                "MCP server started with validation errors - service may not work correctly",
-                "WARNING",
-                {"validation_errors": validation_errors, "error_count": len(validation_errors)}
-            )
-        else:
-            log_structured_entry("All validations passed - MCP server initialization complete", "INFO")
-
-        yield AppContext(
-            vector_search=vs,
-            genai_client=genai_client,
-            settings=cfg,
-        )
-
-    except Exception as e:
-        log_structured_entry(
-            "Failed to initialize MCP server",
-            "ERROR",
-            {
-                "error": str(e),
-                "error_type": type(e).__name__,
-            }
-        )
-        raise
-    finally:
-        log_structured_entry("MCP server lifespan ending", "INFO")
-        # Clean up resources
-        if vs is not None:
-            try:
-                await vs.close()
-                log_structured_entry("Closed aiohttp sessions", "INFO")
-            except Exception as e:
-                log_structured_entry(
-                    "Error closing aiohttp sessions",
-                    "WARNING",
-                    {"error": str(e), "error_type": type(e).__name__}
-                )
-
 
 mcp = FastMCP(
     "knowledge-search",
@@ -733,108 +19,6 @@ mcp = FastMCP(
 )
 
 
-async def _generate_query_embedding(
-    genai_client: genai.Client,
-    embedding_model: str,
-    query: str,
-) -> tuple[list[float], str | None]:
-    """Generate embedding for search query.
-
-    Returns:
-        Tuple of (embedding vector, error message). Error message is None on success.
-    """
-    if not query or not query.strip():
-        return ([], "Error: Query cannot be empty")
-
-    log_structured_entry("Generating query embedding", "INFO")
-    try:
-        response = await genai_client.aio.models.embed_content(
-            model=embedding_model,
-            contents=query,
-            config=genai_types.EmbedContentConfig(
-                task_type="RETRIEVAL_QUERY",
-            ),
-        )
-        embedding = response.embeddings[0].values
-        return (embedding, None)
-    except Exception as e:
-        error_type = type(e).__name__
-        error_msg = str(e)
-
-        # Check if it's a rate limit error
-        if "429" in error_msg or "RESOURCE_EXHAUSTED" in error_msg:
-            log_structured_entry(
-                "Rate limit exceeded while generating embedding",
-                "WARNING",
-                {
-                    "error": error_msg,
-                    "error_type": error_type,
-                    "query": query[:100]
-                }
-            )
-            return ([], "Error: API rate limit exceeded. Please try again later.")
-        else:
-            log_structured_entry(
-                "Failed to generate query embedding",
-                "ERROR",
-                {
-                    "error": error_msg,
-                    "error_type": error_type,
-                    "query": query[:100]
-                }
-            )
-            return ([], f"Error generating embedding: {error_msg}")
-
-
-def _filter_search_results(
-    results: list[SearchResult],
-    min_similarity: float = 0.6,
-    top_percent: float = 0.9,
-) -> list[SearchResult]:
-    """Filter search results by similarity thresholds.
-
-    Args:
-        results: Raw search results from vector search.
-        min_similarity: Minimum similarity score (distance) to include.
-        top_percent: Keep results within this percentage of the top score.
-
-    Returns:
-        Filtered list of search results.
-    """
-    if not results:
-        return []
-
-    max_sim = max(r["distance"] for r in results)
-    cutoff = max_sim * top_percent
-
-    filtered = [
-        s
-        for s in results
-        if s["distance"] > cutoff and s["distance"] > min_similarity
-    ]
-
-    return filtered
-
-
-def _format_search_results(results: list[SearchResult]) -> str:
-    """Format search results as XML-like documents.
-
-    Args:
-        results: List of search results to format.
-
-    Returns:
-        Formatted string with document tags.
-    """
-    if not results:
-        return "No relevant documents found for your query."
-
-    formatted_results = [
-        f"<document {i} name={result['id']}>\n{result['content']}\n</document {i}>"
-        for i, result in enumerate(results, start=1)
-    ]
-    return "\n".join(formatted_results)
-
-
 @mcp.tool()
 async def knowledge_search(
     query: str,
@@ -865,7 +49,7 @@ async def knowledge_search(
 
     try:
         # Generate embedding for the query
-        embedding, error = await _generate_query_embedding(
+        embedding, error = await generate_query_embedding(
             app.genai_client,
             app.settings.embedding_model,
             query,
@@ -903,7 +87,7 @@ async def knowledge_search(
             return f"Error performing vector search: {str(e)}"
 
         # Apply similarity filtering
-        filtered_results = _filter_search_results(search_results)
+        filtered_results = filter_search_results(search_results)
 
         log_structured_entry(
             "knowledge_search completed successfully",
@@ -926,7 +110,7 @@ async def knowledge_search(
                 {"query": query[:100]}
             )
 
-        return _format_search_results(filtered_results)
+        return format_search_results(filtered_results)
 
     except Exception as e:
         # Catch-all for any unexpected errors

src/knowledge_search_mcp/models.py

@@ -0,0 +1,37 @@
+# ruff: noqa: INP001
+"""Domain models for knowledge search MCP server."""
+
+from dataclasses import dataclass
+from enum import Enum
+from typing import TYPE_CHECKING, TypedDict
+
+if TYPE_CHECKING:
+    from google import genai
+
+    from .clients.vector_search import GoogleCloudVectorSearch
+    from .config import Settings
+
+
+class SourceNamespace(str, Enum):
+    """Allowed values for the 'source' namespace filter."""
+
+    EDUCACION_FINANCIERA = "Educacion Financiera"
+    PRODUCTOS_Y_SERVICIOS = "Productos y Servicios"
+    FUNCIONALIDADES_APP_MOVIL = "Funcionalidades de la App Movil"
+
+
+class SearchResult(TypedDict):
+    """Structured response item returned by the vector search API."""
+
+    id: str
+    distance: float
+    content: str
+
+
+@dataclass
+class AppContext:
+    """Shared resources initialised once at server startup."""
+
+    vector_search: "GoogleCloudVectorSearch"
+    genai_client: "genai.Client"
+    settings: "Settings"

src/knowledge_search_mcp/server.py

@@ -0,0 +1,129 @@
+# ruff: noqa: INP001
+"""MCP server lifecycle management."""
+
+from collections.abc import AsyncIterator
+from contextlib import asynccontextmanager
+
+from google import genai
+from mcp.server.fastmcp import FastMCP
+
+from .clients.vector_search import GoogleCloudVectorSearch
+from .config import Settings, cfg
+from .logging import log_structured_entry
+from .models import AppContext
+from .services.validation import (
+    validate_genai_access,
+    validate_gcs_access,
+    validate_vector_search_access,
+)
+
+
+@asynccontextmanager
+async def lifespan(_server: FastMCP) -> AsyncIterator[AppContext]:
+    """Create and configure the vector-search client for the server lifetime."""
+    log_structured_entry(
+        "Initializing MCP server",
+        "INFO",
+        {
+            "project_id": cfg.project_id,
+            "location": cfg.location,
+            "bucket": cfg.bucket,
+            "index_name": cfg.index_name,
+        }
+    )
+
+    vs: GoogleCloudVectorSearch | None = None
+    try:
+        # Initialize vector search client
+        log_structured_entry("Creating GoogleCloudVectorSearch client", "INFO")
+        vs = GoogleCloudVectorSearch(
+            project_id=cfg.project_id,
+            location=cfg.location,
+            bucket=cfg.bucket,
+            index_name=cfg.index_name,
+        )
+
+        # Configure endpoint
+        log_structured_entry(
+            "Configuring index endpoint",
+            "INFO",
+            {
+                "endpoint_name": cfg.endpoint_name,
+                "endpoint_domain": cfg.endpoint_domain,
+            }
+        )
+        vs.configure_index_endpoint(
+            name=cfg.endpoint_name,
+            public_domain=cfg.endpoint_domain,
+        )
+
+        # Initialize GenAI client
+        log_structured_entry(
+            "Creating GenAI client",
+            "INFO",
+            {"project_id": cfg.project_id, "location": cfg.location}
+        )
+        genai_client = genai.Client(
+            vertexai=True,
+            project=cfg.project_id,
+            location=cfg.location,
+        )
+
+        # Validate credentials and configuration by testing actual resources
+        # These validations are non-blocking - errors are logged but won't stop startup
+        log_structured_entry("Starting validation of credentials and resources", "INFO")
+
+        validation_errors = []
+
+        # Run all validations
+        genai_error = await validate_genai_access(genai_client, cfg)
+        if genai_error:
+            validation_errors.append(genai_error)
+
+        gcs_error = await validate_gcs_access(vs, cfg)
+        if gcs_error:
+            validation_errors.append(gcs_error)
+
+        vs_error = await validate_vector_search_access(vs, cfg)
+        if vs_error:
+            validation_errors.append(vs_error)
+
+        # Summary of validations
+        if validation_errors:
+            log_structured_entry(
+                "MCP server started with validation errors - service may not work correctly",
+                "WARNING",
+                {"validation_errors": validation_errors, "error_count": len(validation_errors)}
+            )
+        else:
+            log_structured_entry("All validations passed - MCP server initialization complete", "INFO")
+
+        yield AppContext(
+            vector_search=vs,
+            genai_client=genai_client,
+            settings=cfg,
+        )
+
+    except Exception as e:
+        log_structured_entry(
+            "Failed to initialize MCP server",
+            "ERROR",
+            {
+                "error": str(e),
+                "error_type": type(e).__name__,
+            }
+        )
+        raise
+    finally:
+        log_structured_entry("MCP server lifespan ending", "INFO")
+        # Clean up resources
+        if vs is not None:
+            try:
+                await vs.close()
+                log_structured_entry("Closed aiohttp sessions", "INFO")
+            except Exception as e:
+                log_structured_entry(
+                    "Error closing aiohttp sessions",
+                    "WARNING",
+                    {"error": str(e), "error_type": type(e).__name__}
+                )

src/knowledge_search_mcp/services/__init__.py

@@ -0,0 +1,13 @@
+"""Service modules for business logic."""
+
+from .search import filter_search_results, format_search_results, generate_query_embedding
+from .validation import validate_genai_access, validate_gcs_access, validate_vector_search_access
+
+__all__ = [
+    "filter_search_results",
+    "format_search_results",
+    "generate_query_embedding",
+    "validate_genai_access",
+    "validate_gcs_access",
+    "validate_vector_search_access",
+]

src/knowledge_search_mcp/services/search.py

@@ -0,0 +1,110 @@
+# ruff: noqa: INP001
+"""Search helper functions."""
+
+from google import genai
+from google.genai import types as genai_types
+
+from ..logging import log_structured_entry
+from ..models import SearchResult
+
+
+async def generate_query_embedding(
+    genai_client: genai.Client,
+    embedding_model: str,
+    query: str,
+) -> tuple[list[float], str | None]:
+    """Generate embedding for search query.
+
+    Returns:
+        Tuple of (embedding vector, error message). Error message is None on success.
+    """
+    if not query or not query.strip():
+        return ([], "Error: Query cannot be empty")
+
+    log_structured_entry("Generating query embedding", "INFO")
+    try:
+        response = await genai_client.aio.models.embed_content(
+            model=embedding_model,
+            contents=query,
+            config=genai_types.EmbedContentConfig(
+                task_type="RETRIEVAL_QUERY",
+            ),
+        )
+        embedding = response.embeddings[0].values
+        return (embedding, None)
+    except Exception as e:
+        error_type = type(e).__name__
+        error_msg = str(e)
+
+        # Check if it's a rate limit error
+        if "429" in error_msg or "RESOURCE_EXHAUSTED" in error_msg:
+            log_structured_entry(
+                "Rate limit exceeded while generating embedding",
+                "WARNING",
+                {
+                    "error": error_msg,
+                    "error_type": error_type,
+                    "query": query[:100]
+                }
+            )
+            return ([], "Error: API rate limit exceeded. Please try again later.")
+        else:
+            log_structured_entry(
+                "Failed to generate query embedding",
+                "ERROR",
+                {
+                    "error": error_msg,
+                    "error_type": error_type,
+                    "query": query[:100]
+                }
+            )
+            return ([], f"Error generating embedding: {error_msg}")
+
+
+def filter_search_results(
+    results: list[SearchResult],
+    min_similarity: float = 0.6,
+    top_percent: float = 0.9,
+) -> list[SearchResult]:
+    """Filter search results by similarity thresholds.
+
+    Args:
+        results: Raw search results from vector search.
+        min_similarity: Minimum similarity score (distance) to include.
+        top_percent: Keep results within this percentage of the top score.
+
+    Returns:
+        Filtered list of search results.
+    """
+    if not results:
+        return []
+
+    max_sim = max(r["distance"] for r in results)
+    cutoff = max_sim * top_percent
+
+    filtered = [
+        s
+        for s in results
+        if s["distance"] > cutoff and s["distance"] > min_similarity
+    ]
+
+    return filtered
+
+
+def format_search_results(results: list[SearchResult]) -> str:
+    """Format search results as XML-like documents.
+
+    Args:
+        results: List of search results to format.
+
+    Returns:
+        Formatted string with document tags.
+    """
+    if not results:
+        return "No relevant documents found for your query."
+
+    formatted_results = [
+        f"<document {i} name={result['id']}>\n{result['content']}\n</document {i}>"
+        for i, result in enumerate(results, start=1)
+    ]
+    return "\n".join(formatted_results)

src/knowledge_search_mcp/services/validation.py

@@ -0,0 +1,171 @@
+# ruff: noqa: INP001
+"""Validation functions for Google Cloud services."""
+
+from gcloud.aio.auth import Token
+from google import genai
+from google.genai import types as genai_types
+
+from ..clients.vector_search import GoogleCloudVectorSearch
+from ..config import Settings
+from ..logging import log_structured_entry
+
+
+async def validate_genai_access(genai_client: genai.Client, cfg: Settings) -> str | None:
+    """Validate GenAI embedding access.
+
+    Returns:
+        Error message if validation fails, None if successful.
+    """
+    log_structured_entry("Validating GenAI embedding access", "INFO")
+    try:
+        test_response = await genai_client.aio.models.embed_content(
+            model=cfg.embedding_model,
+            contents="test",
+            config=genai_types.EmbedContentConfig(
+                task_type="RETRIEVAL_QUERY",
+            ),
+        )
+        if test_response and test_response.embeddings:
+            embedding_values = test_response.embeddings[0].values
+            log_structured_entry(
+                "GenAI embedding validation successful",
+                "INFO",
+                {"embedding_dimension": len(embedding_values) if embedding_values else 0}
+            )
+            return None
+        else:
+            msg = "Embedding validation returned empty response"
+            log_structured_entry(msg, "WARNING")
+            return msg
+    except Exception as e:
+        log_structured_entry(
+            "Failed to validate GenAI embedding access - service may not work correctly",
+            "WARNING",
+            {"error": str(e), "error_type": type(e).__name__}
+        )
+        return f"GenAI: {str(e)}"
+
+
+async def validate_gcs_access(vs: GoogleCloudVectorSearch, cfg: Settings) -> str | None:
+    """Validate GCS bucket access.
+
+    Returns:
+        Error message if validation fails, None if successful.
+    """
+    log_structured_entry(
+        "Validating GCS bucket access",
+        "INFO",
+        {"bucket": cfg.bucket}
+    )
+    try:
+        session = vs.storage._get_aio_session()
+        token_obj = Token(
+            session=session,
+            scopes=["https://www.googleapis.com/auth/cloud-platform"],
+        )
+        access_token = await token_obj.get()
+        headers = {"Authorization": f"Bearer {access_token}"}
+
+        async with session.get(
+            f"https://storage.googleapis.com/storage/v1/b/{cfg.bucket}/o?maxResults=1",
+            headers=headers,
+        ) as response:
+            if response.status == 403:
+                msg = f"Access denied to bucket '{cfg.bucket}'. Check permissions."
+                log_structured_entry(
+                    "GCS bucket validation failed - access denied - service may not work correctly",
+                    "WARNING",
+                    {"bucket": cfg.bucket, "status": response.status}
+                )
+                return msg
+            elif response.status == 404:
+                msg = f"Bucket '{cfg.bucket}' not found. Check bucket name and project."
+                log_structured_entry(
+                    "GCS bucket validation failed - not found - service may not work correctly",
+                    "WARNING",
+                    {"bucket": cfg.bucket, "status": response.status}
+                )
+                return msg
+            elif not response.ok:
+                body = await response.text()
+                msg = f"Failed to access bucket '{cfg.bucket}': {response.status}"
+                log_structured_entry(
+                    "GCS bucket validation failed - service may not work correctly",
+                    "WARNING",
+                    {"bucket": cfg.bucket, "status": response.status, "response": body}
+                )
+                return msg
+            else:
+                log_structured_entry(
+                    "GCS bucket validation successful",
+                    "INFO",
+                    {"bucket": cfg.bucket}
+                )
+                return None
+    except Exception as e:
+        log_structured_entry(
+            "Failed to validate GCS bucket access - service may not work correctly",
+            "WARNING",
+            {"error": str(e), "error_type": type(e).__name__, "bucket": cfg.bucket}
+        )
+        return f"GCS: {str(e)}"
+
+
+async def validate_vector_search_access(vs: GoogleCloudVectorSearch, cfg: Settings) -> str | None:
+    """Validate vector search endpoint access.
+
+    Returns:
+        Error message if validation fails, None if successful.
+    """
+    log_structured_entry(
+        "Validating vector search endpoint access",
+        "INFO",
+        {"endpoint_name": cfg.endpoint_name}
+    )
+    try:
+        headers = await vs._async_get_auth_headers()
+        session = vs._get_aio_session()
+        endpoint_url = (
+            f"https://{cfg.location}-aiplatform.googleapis.com/v1/{cfg.endpoint_name}"
+        )
+
+        async with session.get(endpoint_url, headers=headers) as response:
+            if response.status == 403:
+                msg = f"Access denied to endpoint '{cfg.endpoint_name}'. Check permissions."
+                log_structured_entry(
+                    "Vector search endpoint validation failed - access denied - service may not work correctly",
+                    "WARNING",
+                    {"endpoint": cfg.endpoint_name, "status": response.status}
+                )
+                return msg
+            elif response.status == 404:
+                msg = f"Endpoint '{cfg.endpoint_name}' not found. Check endpoint name and project."
+                log_structured_entry(
+                    "Vector search endpoint validation failed - not found - service may not work correctly",
+                    "WARNING",
+                    {"endpoint": cfg.endpoint_name, "status": response.status}
+                )
+                return msg
+            elif not response.ok:
+                body = await response.text()
+                msg = f"Failed to access endpoint '{cfg.endpoint_name}': {response.status}"
+                log_structured_entry(
+                    "Vector search endpoint validation failed - service may not work correctly",
+                    "WARNING",
+                    {"endpoint": cfg.endpoint_name, "status": response.status, "response": body}
+                )
+                return msg
+            else:
+                log_structured_entry(
+                    "Vector search endpoint validation successful",
+                    "INFO",
+                    {"endpoint": cfg.endpoint_name}
+                )
+                return None
+    except Exception as e:
+        log_structured_entry(
+            "Failed to validate vector search endpoint access - service may not work correctly",
+            "WARNING",
+            {"error": str(e), "error_type": type(e).__name__, "endpoint": cfg.endpoint_name}
+        )
+        return f"Vector Search: {str(e)}"

src/knowledge_search_mcp/utils/__init__.py

@@ -0,0 +1,5 @@
+"""Utility modules for knowledge search MCP server."""
+
+from .cache import LRUCache
+
+__all__ = ["LRUCache"]

src/knowledge_search_mcp/utils/cache.py

@@ -0,0 +1,33 @@
+# ruff: noqa: INP001
+"""LRU cache implementation."""
+
+from collections import OrderedDict
+
+
+class LRUCache:
+    """Simple LRU cache with size limit."""
+
+    def __init__(self, max_size: int = 100) -> None:
+        """Initialize cache with maximum size."""
+        self.cache: OrderedDict[str, bytes] = OrderedDict()
+        self.max_size = max_size
+
+    def get(self, key: str) -> bytes | None:
+        """Get item from cache, returning None if not found."""
+        if key not in self.cache:
+            return None
+        # Move to end to mark as recently used
+        self.cache.move_to_end(key)
+        return self.cache[key]
+
+    def put(self, key: str, value: bytes) -> None:
+        """Put item in cache, evicting oldest if at capacity."""
+        if key in self.cache:
+            self.cache.move_to_end(key)
+        self.cache[key] = value
+        if len(self.cache) > self.max_size:
+            self.cache.popitem(last=False)
+
+    def __contains__(self, key: str) -> bool:
+        """Check if key exists in cache."""
+        return key in self.cache

tests/test_search.py

@@ -5,7 +5,7 @@ from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
 
-from knowledge_search_mcp.main import (
+from knowledge_search_mcp import (
     GoogleCloudFileStorage,
     GoogleCloudVectorSearch,
     LRUCache,