openrpc-mpc-server

Instructions

Implementation Reference

• src/index.ts:93-109 (handler)

  The switch case handling 'rpc_call': extracts server URL, method, and params from arguments; creates HTTPTransport and Client from @open-rpc/client-js; calls the JSON-RPC method; returns the result as a text content block with formatted JSON.

  case "rpc_call": {
    const server = String(request.params.arguments?.server);
    const method = String(request.params.arguments?.method);
    const params = JSON.parse(String(request.params.arguments?.params));
    let transport = new HTTPTransport(server);
    let client = new Client(new RequestManager([transport]));
    const results = await client.request({ method: method, params: params as any});
    return {
      toolResult: {
        content: [{
          type: "text",
          text: JSON.stringify(results, null, 2)
        }],
        isError: false
      }
    };
  }

• src/index.ts:45-67 (registration)

  Registers the 'rpc_call' tool in the ListTools response, including its name, description, and inputSchema defining server (string, required), method (string, required), and optional stringified params.

  {
    name: "rpc_call",
    description: "Call any JSON-RPC method on a server with parameters. A user would prompt: Call method <method> on <server url> with params <params>",
    inputSchema: {
      type: "object",
      properties: {
        server: {
          type: "string", 
          description: "Server URL"
        },
        method: {
          type: "string",
          description: "JSON-RPC method name to call"
        },
        // this is a bit of a hack since claude seems to have issues with nested parameters
        params: {
          type: "string",
          description: "Stringified Parameters to pass to the method"
        } 
      },
      required: ["server", "method"]
    }
  },

• src/index.ts:48-66 (schema)

  Input schema for rpc_call tool: object with required 'server' and 'method' strings, optional 'params' as string (JSON stringified).

  inputSchema: {
    type: "object",
    properties: {
      server: {
        type: "string", 
        description: "Server URL"
      },
      method: {
        type: "string",
        description: "JSON-RPC method name to call"
      },
      // this is a bit of a hack since claude seems to have issues with nested parameters
      params: {
        type: "string",
        description: "Stringified Parameters to pass to the method"
      } 
    },
    required: ["server", "method"]
  }