"""FastMCP server implementation for OpenAPI integration.""" import re from collections import Counter from typing import Any, Literal import httpx from jsonschema_path import SchemaPath # Import from our new utilities and components from fastmcp.experimental.utilities.openapi import ( HTTPRoute, extract_output_schema_from_responses, format_simple_description, parse_openapi_to_http_routes, ) from fastmcp.experimental.utilities.openapi.director import RequestDirector from fastmcp.server.server import FastMCP from fastmcp.utilities.logging import get_logger from .components import ( OpenAPIResource, OpenAPIResourceTemplate, OpenAPITool, ) from .routing import ( DEFAULT_ROUTE_MAPPINGS, ComponentFn, MCPType, RouteMap, RouteMapFn, _determine_route_type, ) logger = get_logger(__name__) def _slugify(text: str) -> str: """ Convert text to a URL-friendly slug format that only contains lowercase letters, uppercase letters, numbers, and underscores. """ if not text: return "" # Replace spaces and common separators with underscores slug = re.sub(r"[\s\-\.]+", "_", text) # Remove non-alphanumeric characters except underscores slug = re.sub(r"[^a-zA-Z0-9_]", "", slug) # Remove multiple consecutive underscores slug = re.sub(r"_+", "_", slug) # Remove leading/trailing underscores slug = slug.strip("_") return slug class FastMCPOpenAPI(FastMCP): """ FastMCP server implementation that creates components from an OpenAPI schema. This class parses an OpenAPI specification and creates appropriate FastMCP components (Tools, Resources, ResourceTemplates) based on route mappings. Example: ```python from fastmcp.server.openapi import FastMCPOpenAPI, RouteMap, MCPType import httpx # Define custom route mappings custom_mappings = [ # Map all user-related endpoints to ResourceTemplate RouteMap( methods=["GET", "POST", "PATCH"], pattern=r".*/users/.*", mcp_type=MCPType.RESOURCE_TEMPLATE ), # Map all analytics endpoints to Tool RouteMap( methods=["GET"], pattern=r".*/analytics/.*", mcp_type=MCPType.TOOL ), ] # Create server with custom mappings and route mapper server = FastMCPOpenAPI( openapi_spec=spec, client=httpx.AsyncClient(), name="API Server", route_maps=custom_mappings, ) ``` """ def __init__( self, openapi_spec: dict[str, Any], client: httpx.AsyncClient, name: str | None = None, route_maps: list[RouteMap] | None = None, route_map_fn: RouteMapFn | None = None, mcp_component_fn: ComponentFn | None = None, mcp_names: dict[str, str] | None = None, tags: set[str] | None = None, timeout: float | None = None, **settings: Any, ): """ Initialize a FastMCP server from an OpenAPI schema. Args: openapi_spec: OpenAPI schema as a dictionary or file path client: httpx AsyncClient for making HTTP requests name: Optional name for the server route_maps: Optional list of RouteMap objects defining route mappings route_map_fn: Optional callable for advanced route type mapping. Receives (route, mcp_type) and returns MCPType or None. Called on every route, including excluded ones. mcp_component_fn: Optional callable for component customization. Receives (route, component) and can modify the component in-place. Called on every created component. mcp_names: Optional dictionary mapping operationId to desired component names. If an operationId is not in the dictionary, falls back to using the operationId up to the first double underscore. If no operationId exists, falls back to slugified summary or path-based naming. All names are truncated to 56 characters maximum. tags: Optional set of tags to add to all components. Components always receive any tags from the route. timeout: Optional timeout (in seconds) for all requests **settings: Additional settings for FastMCP """ super().__init__(name=name or "OpenAPI FastMCP", **settings) self._client = client self._timeout = timeout self._mcp_component_fn = mcp_component_fn # Keep track of names to detect collisions self._used_names = { "tool": Counter(), "resource": Counter(), "resource_template": Counter(), "prompt": Counter(), } # Create openapi-core Spec and RequestDirector for stateless request building try: self._spec = SchemaPath.from_dict(openapi_spec) # type: ignore[arg-type] self._director = RequestDirector(self._spec) except Exception as e: logger.error(f"Failed to initialize RequestDirector: {e}") raise ValueError(f"Invalid OpenAPI specification: {e}") from e http_routes = parse_openapi_to_http_routes(openapi_spec) # Process routes route_maps = (route_maps or []) + DEFAULT_ROUTE_MAPPINGS for route in http_routes: # Determine route type based on mappings or default rules route_map = _determine_route_type(route, route_maps) route_type = route_map.mcp_type # Call route_map_fn if provided if route_map_fn is not None: try: result = route_map_fn(route, route_type) if result is not None: route_type = result logger.debug( f"Route {route.method} {route.path} mapping customized by route_map_fn: " f"type={route_type.name}" ) except Exception as e: logger.warning( f"Error in route_map_fn for {route.method} {route.path}: {e}. " f"Using default values." ) # Generate a default name from the route component_name = self._generate_default_name(route, mcp_names) route_tags = set(route.tags) | route_map.mcp_tags | (tags or set()) # Create components using simplified approach with RequestDirector if route_type == MCPType.TOOL: self._create_openapi_tool(route, component_name, tags=route_tags) elif route_type == MCPType.RESOURCE: self._create_openapi_resource(route, component_name, tags=route_tags) elif route_type == MCPType.RESOURCE_TEMPLATE: self._create_openapi_template(route, component_name, tags=route_tags) elif route_type == MCPType.EXCLUDE: logger.debug(f"Excluding route: {route.method} {route.path}") logger.debug(f"Created FastMCP OpenAPI server with {len(http_routes)} routes") def _generate_default_name( self, route: HTTPRoute, mcp_names_map: dict[str, str] | None = None ) -> str: """Generate a default name from the route using the configured strategy.""" name = "" mcp_names_map = mcp_names_map or {} # First check if there's a custom mapping for this operationId if route.operation_id: if route.operation_id in mcp_names_map: name = mcp_names_map[route.operation_id] else: # If there's a double underscore in the operationId, use the first part name = route.operation_id.split("__")[0] else: name = route.summary or f"{route.method}_{route.path}" name = _slugify(name) # Truncate to 56 characters maximum if len(name) > 56: name = name[:56] return name def _get_unique_name( self, name: str, component_type: Literal["tool", "resource", "resource_template", "prompt"], ) -> str: """ Ensure the name is unique within its component type by appending numbers if needed. Args: name: The proposed name component_type: The type of component ("tools", "resources", or "templates") Returns: str: A unique name for the component """ # Check if the name is already used self._used_names[component_type][name] += 1 if self._used_names[component_type][name] == 1: return name else: # Create the new name new_name = f"{name}_{self._used_names[component_type][name]}" logger.debug( f"Name collision detected: '{name}' already exists as a {component_type[:-1]}. " f"Using '{new_name}' instead." ) return new_name def _create_openapi_tool( self, route: HTTPRoute, name: str, tags: set[str], ): """Creates and registers an OpenAPITool with enhanced description.""" # Use pre-calculated schema from route combined_schema = route.flat_param_schema # Extract output schema from OpenAPI responses output_schema = extract_output_schema_from_responses( route.responses, route.response_schemas, route.openapi_version, ) # Get a unique tool name tool_name = self._get_unique_name(name, "tool") base_description = ( route.description or route.summary or f"Executes {route.method} {route.path}" ) # Use simplified description formatter for tools enhanced_description = format_simple_description( base_description=base_description, parameters=route.parameters, request_body=route.request_body, ) tool = OpenAPITool( client=self._client, route=route, director=self._director, name=tool_name, description=enhanced_description, parameters=combined_schema, output_schema=output_schema, tags=set(route.tags or []) | tags, timeout=self._timeout, ) # Call component_fn if provided if self._mcp_component_fn is not None: try: self._mcp_component_fn(route, tool) logger.debug(f"Tool {tool_name} customized by component_fn") except Exception as e: logger.warning( f"Error in component_fn for tool {tool_name}: {e}. " f"Using component as-is." ) # Use the potentially modified tool name as the registration key final_tool_name = tool.name # Register the tool by directly assigning to the tools dictionary self._tool_manager._tools[final_tool_name] = tool def _create_openapi_resource( self, route: HTTPRoute, name: str, tags: set[str], ): """Creates and registers an OpenAPIResource with enhanced description.""" # Get a unique resource name resource_name = self._get_unique_name(name, "resource") resource_uri = f"resource://{resource_name}" base_description = ( route.description or route.summary or f"Represents {route.path}" ) # Use simplified description for resources enhanced_description = format_simple_description( base_description=base_description, parameters=route.parameters, request_body=route.request_body, ) resource = OpenAPIResource( client=self._client, route=route, director=self._director, uri=resource_uri, name=resource_name, description=enhanced_description, tags=set(route.tags or []) | tags, timeout=self._timeout, ) # Call component_fn if provided if self._mcp_component_fn is not None: try: self._mcp_component_fn(route, resource) logger.debug(f"Resource {resource_uri} customized by component_fn") except Exception as e: logger.warning( f"Error in component_fn for resource {resource_uri}: {e}. " f"Using component as-is." ) # Use the potentially modified resource URI as the registration key final_resource_uri = str(resource.uri) # Register the resource by directly assigning to the resources dictionary self._resource_manager._resources[final_resource_uri] = resource def _create_openapi_template( self, route: HTTPRoute, name: str, tags: set[str], ): """Creates and registers an OpenAPIResourceTemplate with enhanced description.""" # Get a unique template name template_name = self._get_unique_name(name, "resource_template") path_params = [p.name for p in route.parameters if p.location == "path"] path_params.sort() # Sort for consistent URIs uri_template_str = f"resource://{template_name}" if path_params: uri_template_str += "/" + "/".join(f"{{{p}}}" for p in path_params) base_description = ( route.description or route.summary or f"Template for {route.path}" ) # Use simplified description for resource templates enhanced_description = format_simple_description( base_description=base_description, parameters=route.parameters, request_body=route.request_body, ) template_params_schema = { "type": "object", "properties": { p.name: { **(p.schema_.copy() if isinstance(p.schema_, dict) else {}), **( {"description": p.description} if p.description and not ( isinstance(p.schema_, dict) and "description" in p.schema_ ) else {} ), } for p in route.parameters if p.location == "path" }, "required": [ p.name for p in route.parameters if p.location == "path" and p.required ], } template = OpenAPIResourceTemplate( client=self._client, route=route, director=self._director, uri_template=uri_template_str, name=template_name, description=enhanced_description, parameters=template_params_schema, tags=set(route.tags or []) | tags, timeout=self._timeout, ) # Call component_fn if provided if self._mcp_component_fn is not None: try: self._mcp_component_fn(route, template) logger.debug(f"Template {uri_template_str} customized by component_fn") except Exception as e: logger.warning( f"Error in component_fn for template {uri_template_str}: {e}. " f"Using component as-is." ) # Use the potentially modified template URI as the registration key final_template_uri = template.uri_template # Register the template by directly assigning to the templates dictionary self._resource_manager._templates[final_template_uri] = template # Export public symbols __all__ = [ "FastMCPOpenAPI", ]