Hono MCP Generator

Getting Started

To install dependencies:

bun install

To generate OpenAPI spec, along with client SDK and MCP app:

bun client:gen

Then un-comment the mcpApp import and routing in src/index.ts:

import mcpApp from '../sdk/mcp.gen';
// ...
app.route('/mcp', mcpApp);

To run:

bun dev

open http://localhost:3000

To launch MCP inspector:

bun mcp:inspector

Testing

1. Set the MCP Inspector target URL to http://localhost:3000/mcp.

2. Select Connect, then List Tools.

3. Select the Get User tool.

4. Add an arbitrary ID value as a path parameter.

5. Select Run Tool.

6. The returned mock User should have the ID value you entered!

Notes

• Client generation fails on any TypeScript errors, so the initial generated MCP import must be commented-out.
• The @modelcontextprotocol/sdk dependency is only compatible with Zod 3, so the openapi-ts config was updated accordingly.
• Paths in the openapi-ts config were updated to be compatible with this project's structure.
• The api-config.ts file depends on a generated type file, which seems a little fragile, but doesn't cause any compile-time problems.
• The api-config.ts file was modified to directly include clientConfig, and project-specific values like appConfig and ApiError were removed for simplicity.

Roadmap

• The registerTool method is recommended over tool for more robust use-cases.
• It may be helpful to add a List Tools MCP endpoint to help clients discover available tools and resources.
• Passing auth credentials via MCP is not currently supported.