"""Resource-related methods for FastMCP Client.""" from __future__ import annotations import uuid import weakref from typing import TYPE_CHECKING, Any, Literal, cast, overload import mcp.types from pydantic import AnyUrl, RootModel if TYPE_CHECKING: from fastmcp.client.client import Client from fastmcp.client.tasks import ResourceTask from fastmcp.client.telemetry import client_span from fastmcp.telemetry import inject_trace_context from fastmcp.utilities.logging import get_logger logger = get_logger(__name__) AUTO_PAGINATION_MAX_PAGES = 250 # Type alias for task response union (SEP-1686 graceful degradation) ResourceTaskResponseUnion = RootModel[ mcp.types.CreateTaskResult | mcp.types.ReadResourceResult ] class ClientResourcesMixin: """Mixin providing resource-related methods for Client.""" # --- Resources --- async def list_resources_mcp( self: Client, *, cursor: str | None = None ) -> mcp.types.ListResourcesResult: """Send a resources/list request and return the complete MCP protocol result. Args: cursor: Optional pagination cursor from a previous request's nextCursor. Returns: mcp.types.ListResourcesResult: The complete response object from the protocol, containing the list of resources and any additional metadata. Raises: RuntimeError: If called while the client is not connected. McpError: If the request results in a TimeoutError | JSONRPCError """ with client_span( "resources/list", "resources/list", "", session_id=self.transport.get_session_id(), ): logger.debug(f"[{self.name}] called list_resources") result = await self._await_with_session_monitoring( self.session.list_resources(cursor=cursor) ) return result async def list_resources( self: Client, max_pages: int = AUTO_PAGINATION_MAX_PAGES, ) -> list[mcp.types.Resource]: """Retrieve all resources available on the server. This method automatically fetches all pages if the server paginates results, returning the complete list. For manual pagination control (e.g., to handle large result sets incrementally), use list_resources_mcp() with the cursor parameter. Args: max_pages: Maximum number of pages to fetch before raising. Defaults to 250. Returns: list[mcp.types.Resource]: A list of all Resource objects. Raises: RuntimeError: If the page limit is reached before pagination completes. McpError: If the request results in a TimeoutError | JSONRPCError """ all_resources: list[mcp.types.Resource] = [] cursor: str | None = None seen_cursors: set[str] = set() for _ in range(max_pages): result = await self.list_resources_mcp(cursor=cursor) all_resources.extend(result.resources) if not result.nextCursor: break if result.nextCursor in seen_cursors: logger.warning( f"[{self.name}] Server returned duplicate pagination cursor" f" {result.nextCursor!r} for list_resources; stopping pagination" ) break seen_cursors.add(result.nextCursor) cursor = result.nextCursor else: raise RuntimeError( f"[{self.name}] Reached auto-pagination limit" f" ({max_pages} pages) for list_resources." " Use list_resources_mcp() with cursor for manual pagination," " or increase max_pages." ) return all_resources async def list_resource_templates_mcp( self: Client, *, cursor: str | None = None ) -> mcp.types.ListResourceTemplatesResult: """Send a resources/listResourceTemplates request and return the complete MCP protocol result. Args: cursor: Optional pagination cursor from a previous request's nextCursor. Returns: mcp.types.ListResourceTemplatesResult: The complete response object from the protocol, containing the list of resource templates and any additional metadata. Raises: RuntimeError: If called while the client is not connected. McpError: If the request results in a TimeoutError | JSONRPCError """ with client_span( "resources/templates/list", "resources/templates/list", "", session_id=self.transport.get_session_id(), ): logger.debug(f"[{self.name}] called list_resource_templates") result = await self._await_with_session_monitoring( self.session.list_resource_templates(cursor=cursor) ) return result async def list_resource_templates( self: Client, max_pages: int = AUTO_PAGINATION_MAX_PAGES, ) -> list[mcp.types.ResourceTemplate]: """Retrieve all resource templates available on the server. This method automatically fetches all pages if the server paginates results, returning the complete list. For manual pagination control (e.g., to handle large result sets incrementally), use list_resource_templates_mcp() with the cursor parameter. Args: max_pages: Maximum number of pages to fetch before raising. Defaults to 250. Returns: list[mcp.types.ResourceTemplate]: A list of all ResourceTemplate objects. Raises: RuntimeError: If the page limit is reached before pagination completes. McpError: If the request results in a TimeoutError | JSONRPCError """ all_templates: list[mcp.types.ResourceTemplate] = [] cursor: str | None = None seen_cursors: set[str] = set() for _ in range(max_pages): result = await self.list_resource_templates_mcp(cursor=cursor) all_templates.extend(result.resourceTemplates) if not result.nextCursor: break if result.nextCursor in seen_cursors: logger.warning( f"[{self.name}] Server returned duplicate pagination cursor" f" {result.nextCursor!r} for list_resource_templates;" " stopping pagination" ) break seen_cursors.add(result.nextCursor) cursor = result.nextCursor else: raise RuntimeError( f"[{self.name}] Reached auto-pagination limit" f" ({max_pages} pages) for list_resource_templates." " Use list_resource_templates_mcp() with cursor for manual pagination," " or increase max_pages." ) return all_templates async def read_resource_mcp( self: Client, uri: AnyUrl | str, meta: dict[str, Any] | None = None ) -> mcp.types.ReadResourceResult: """Send a resources/read request and return the complete MCP protocol result. Args: uri (AnyUrl | str): The URI of the resource to read. Can be a string or an AnyUrl object. meta (dict[str, Any] | None, optional): Request metadata (e.g., for SEP-1686 tasks). Defaults to None. Returns: mcp.types.ReadResourceResult: The complete response object from the protocol, containing the resource contents and any additional metadata. Raises: RuntimeError: If called while the client is not connected. McpError: If the request results in a TimeoutError | JSONRPCError """ uri_str = str(uri) with client_span( "resources/read", "resources/read", uri_str, session_id=self.transport.get_session_id(), resource_uri=uri_str, ): logger.debug(f"[{self.name}] called read_resource: {uri}") if isinstance(uri, str): uri = AnyUrl(uri) # Ensure AnyUrl # Inject trace context into meta for propagation to server propagated_meta = inject_trace_context(meta) request_meta = cast(mcp.types.RequestParams.Meta | None, propagated_meta) # If meta provided, use send_request for SEP-1686 task support if propagated_meta: task_dict = propagated_meta.get("modelcontextprotocol.io/task") request = mcp.types.ReadResourceRequest( params=mcp.types.ReadResourceRequestParams( uri=uri, task=mcp.types.TaskMetadata(**task_dict) if task_dict else None, _meta=request_meta, # type: ignore[unknown-argument] # pydantic alias ) ) result = await self._await_with_session_monitoring( self.session.send_request( request=request, # type: ignore[arg-type] # ty:ignore[invalid-argument-type] result_type=mcp.types.ReadResourceResult, ) ) else: result = await self._await_with_session_monitoring( self.session.read_resource(uri) ) return result @overload async def read_resource( self: Client, uri: AnyUrl | str, *, version: str | None = None, meta: dict[str, Any] | None = None, task: Literal[False] = False, ) -> list[mcp.types.TextResourceContents | mcp.types.BlobResourceContents]: ... @overload async def read_resource( self: Client, uri: AnyUrl | str, *, version: str | None = None, meta: dict[str, Any] | None = None, task: Literal[True], task_id: str | None = None, ttl: int = 60000, ) -> ResourceTask: ... async def read_resource( self: Client, uri: AnyUrl | str, *, version: str | None = None, meta: dict[str, Any] | None = None, task: bool = False, task_id: str | None = None, ttl: int = 60000, ) -> ( list[mcp.types.TextResourceContents | mcp.types.BlobResourceContents] | ResourceTask ): """Read the contents of a resource or resolved template. Args: uri (AnyUrl | str): The URI of the resource to read. Can be a string or an AnyUrl object. version (str | None): Specific version to read. If None, reads highest version. meta (dict[str, Any] | None): Optional request-level metadata. task (bool): If True, execute as background task (SEP-1686). Defaults to False. task_id (str | None): Optional client-provided task ID (auto-generated if not provided). ttl (int): Time to keep results available in milliseconds (default 60s). Returns: list[mcp.types.TextResourceContents | mcp.types.BlobResourceContents] | ResourceTask: A list of content objects if task=False, or a ResourceTask object if task=True. Raises: RuntimeError: If called while the client is not connected. McpError: If the request results in a TimeoutError | JSONRPCError """ # Merge version into request-level meta (not arguments) request_meta = dict(meta) if meta else {} if version is not None: request_meta["fastmcp"] = { **request_meta.get("fastmcp", {}), "version": version, } if task: return await self._read_resource_as_task( uri, task_id, ttl, meta=request_meta or None ) if isinstance(uri, str): try: uri = AnyUrl(uri) # Ensure AnyUrl except Exception as e: raise ValueError( f"Provided resource URI is invalid: {str(uri)!r}" ) from e result = await self.read_resource_mcp(uri, meta=request_meta or None) return result.contents async def _read_resource_as_task( self: Client, uri: AnyUrl | str, task_id: str | None = None, ttl: int = 60000, meta: dict[str, Any] | None = None, ) -> ResourceTask: """Read a resource for background execution (SEP-1686). Returns a ResourceTask object that handles both background and immediate execution. Args: uri: Resource URI to read task_id: Optional client-provided task ID (ignored, for backward compatibility) ttl: Time to keep results available in milliseconds (default 60s) meta: Optional metadata to pass with the request (e.g., version info) Returns: ResourceTask: Future-like object for accessing task status and results """ # Per SEP-1686 final spec: client sends only ttl, server generates taskId # Inject trace context into meta for propagation to server propagated_meta = inject_trace_context(meta) request_meta = cast(mcp.types.RequestParams.Meta | None, propagated_meta) if isinstance(uri, str): uri = AnyUrl(uri) request = mcp.types.ReadResourceRequest( params=mcp.types.ReadResourceRequestParams( uri=uri, task=mcp.types.TaskMetadata(ttl=ttl), _meta=request_meta, # type: ignore[unknown-argument] # pydantic alias ) ) # Server returns CreateTaskResult (task accepted) or ReadResourceResult (graceful degradation) wrapped_result = await self._await_with_session_monitoring( self.session.send_request( request=request, # type: ignore[arg-type] # ty:ignore[invalid-argument-type] result_type=ResourceTaskResponseUnion, ) ) raw_result = wrapped_result.root if isinstance(raw_result, mcp.types.CreateTaskResult): # Task was accepted - extract task info from CreateTaskResult server_task_id = raw_result.task.taskId self._submitted_task_ids.add(server_task_id) task_obj = ResourceTask( self, server_task_id, uri=str(uri), immediate_result=None ) self._task_registry[server_task_id] = weakref.ref(task_obj) return task_obj else: # Graceful degradation - server returned ReadResourceResult synthetic_task_id = task_id or str(uuid.uuid4()) return ResourceTask( self, synthetic_task_id, uri=str(uri), immediate_result=raw_result.contents, )