MetaMask MCP

Instructions

Implementation Reference

• src/tools/connect.ts:11-28 (registration)

  Registration of the 'get-connect-uri' MCP tool, defining name, description, input schema (empty), and execute handler function.

  server.addTool({
    name: "get-connect-uri",
    description: "Get the connect URI to connect to a MetaMask wallet.",
    parameters: z.object({}),
    execute: async (_, { log }) => {
      const uri = await getMetaMaskConnectURI(log, wagmiConfig);
      return {
        content: [
          {
            type: "text",
            text: JSONStringify({
              uri,
            }),
          },
        ],
      };
    },
  });

• src/tools/connect.ts:15-27 (handler)

  Execute handler for 'get-connect-uri' tool: calls helper to get MetaMask connect URI and returns it as structured text content.

  execute: async (_, { log }) => {
    const uri = await getMetaMaskConnectURI(log, wagmiConfig);
    return {
      content: [
        {
          type: "text",
          text: JSONStringify({
            uri,
          }),
        },
      ],
    };
  },

• src/tools/connect.ts:14-14 (schema)

  Zod input schema for 'get-connect-uri': no parameters required.

  parameters: z.object({}),

• src/tools/connect.ts:48-74 (helper)

  Helper function implementing the core logic: creates headless MetaMask connector, listens for 'display_uri' event, and resolves the connect URI.

  async function getMetaMaskConnectURI(log: any, wagmiConfig: Config) {
    return new Promise((resolve, reject) => {
      const connectorFn = metaMask({
        headless: true,
      });
      const connector = wagmiConfig._internal.connectors.setup(connectorFn);
      connector.emitter.on("message", (payload) => {
        if (payload.type === "display_uri") {
          const uri = payload.data;
          resolve(uri);
        }
      });
      connector.emitter.on("connect", (payload) => {
        log.debug("connect success!", payload.accounts);
      });
      connector.emitter.on("error", (payload) => {
        log.error(payload.error);
      });
  
      connect(wagmiConfig, { connector })
        .catch((error) => {
          log.error("connect error: ", error);
          log.error(error.stack);
          reject(error);
        });
    });
  }

• src/tools/register-tools.ts:35-35 (registration)

  Top-level call to register connect tools, including 'get-connect-uri', during overall tools registration.

  registerConnectTools(server, wagmiConfig);