gRPC MCP Server

Instructions

Implementation Reference

• src/loader.ts:46-67 (handler)

  The core handler function that loads the protobuf definition from the given proto file path, searches for the specified service and method, and returns detailed information including request/response message names, associated messages, and enums.

  async getMethodAsync(path: string, service: string, method: string): Promise<Method | undefined> {
      const proto = await protoLoader.loadAsync(path);
  
      let result: Method | undefined = undefined;
      protocolBufferMethodForEach(
          proto.map((p) => p.protocolBuffer),
          (p, s, m) => {
              if (s.name === service && m.name === method) {
                  result = {
                      name: method,
                      request: m.requestMessageName,
                      response: m.responseMessageName,
                      messages: [...p.messages],
                      enums: [...p.enums],
                  };
              }
              return result !== undefined;
          },
      );
  
      return result;
  },

• src/index.ts:61-78 (registration)

  Registers the MCP tool 'getMethodInformation' with the FastMCP server, including input schema validation via Zod and a thin execute wrapper that invokes the core handler and handles errors.

  server.addTool({
      name: "getMethodInformation",
      description: "Get information about methods in a proto file",
      parameters: z.object({
          path: z.string().describe("Path to the proto file (Full path)"),
          service: z.string().describe("Service name (e.g., AddressService)"),
          method: z.string().describe("Method name (e.g., GetAddress)"),
      }),
      execute: async (args) => {
          try {
              const res = await loader.getMethodAsync(args.path, args.service, args.method);
              return obj2String(res, true);
          } catch (e) {
              Logger.error(e);
              return e instanceof Error ? e.message : "An unknown error occurred";
          }
      },
  });

• src/loader.ts:19-24 (schema)

  TypeScript type definition for the output structure returned by the getMethodInformation tool.

      name: string;
      request: string;
      response: string;
      messages: ProtocolBufferMessage[];
      enums: ProtocolBufferEnum[];
  };