Expo MCP Server

Instructions

Implementation Reference

• src/index.ts:63-82 (handler)

  The handler function for the 'listTools' tool. It accesses the internal '_tools' property of the FastMCP server instance to retrieve the list of registered tools, formats them as a markdown-style list in a text content block, and returns it. Includes error handling with logging.

  execute: async (_, { log }) => {
    try {
      // Get all the tools (this is a workaround since we don't have direct access to the tools list)
      const tools = Object.keys((server as any)["_tools"] || {});
  
      return {
        content: [
          {
            type: "text",
            text: `Available tools:\n${tools
              .map((tool) => `- ${tool}`)
              .join("\n")}`,
          },
        ],
      };
    } catch (error: any) {
      log.error(`Error listing tools: ${error.message}`);
      throw new Error(`Failed to list tools: ${error.message}`);
    }
  },

• src/index.ts:59-83 (registration)

  Registration of the 'listTools' tool using server.addTool(). Includes the tool name, description, empty parameters schema (no input required), and points to the inline handler function.

  server.addTool({
    name: "listTools",
    description: "List all available tools in this MCP server",
    parameters: z.object({}),
    execute: async (_, { log }) => {
      try {
        // Get all the tools (this is a workaround since we don't have direct access to the tools list)
        const tools = Object.keys((server as any)["_tools"] || {});
  
        return {
          content: [
            {
              type: "text",
              text: `Available tools:\n${tools
                .map((tool) => `- ${tool}`)
                .join("\n")}`,
            },
          ],
        };
      } catch (error: any) {
        log.error(`Error listing tools: ${error.message}`);
        throw new Error(`Failed to list tools: ${error.message}`);
      }
    },
  });

• src/index.ts:62-62 (schema)

  The Zod schema for listTools input parameters, which is an empty object indicating no input parameters are required.

  parameters: z.object({}),