kubb mcp

Run kubb mcp to start a Model Context Protocol server. LLM clients such as Claude, Cursor, and VS Code can then read your schemas and trigger generation.

WARNING

This feature is under active development. Use it with caution and expect breaking changes.

Terminal

command: kubb mcp
output:
  - ⏳ Starting MCP server...
  - This feature is still under development, use with caution

Usage

Start the MCP server over stdio, the transport every major LLM client speaks:

Terminal

kubb mcp

TIP

@kubb/mcp ships as a dependency of the kubb package, so you need no extra install when you already use kubb.

Transport

kubb mcp runs over stdio. The server reads from standard input and writes to standard output, matching the Model Context Protocol transport used by Claude Desktop, Cursor, VS Code, and other editor integrations. The client launches the server as a subprocess, so it needs no flags, port, or host.

Tools

The MCP server exposes three tools to connected clients.

Tool	Description
generate	Runs the Kubb pipeline against a resolved kubb.config.ts and streams log messages back to the client.
validate	Validates an OpenAPI or Swagger document at a path or URL. Needs @kubb/adapter-oas installed in the project.
init	Scaffolds a kubb.config.ts in the current directory without prompts. It does not install packages.

Structured diagnostics

When generate or validate hits a problem, it returns structured diagnostics instead of a single message string. Each diagnostic keeps its stable code, source pointer, suggested fix, and docs link, so an assistant can act on the exact problem. The tools return a readable text block and a JSON payload:

Terminal

error @kubb/plugin-zod(KUBB_REF_NOT_FOUND): Could not find a definition for #/components/schemas/Pet.
  at #/components/schemas/Pet
  help: Add the schema under components.schemas, or fix the $ref.
  docs: https://kubb.dev/docs/5.x/reference/diagnostics/kubb-ref-not-found

A missing spec passed to validate returns the coded KUBB_INPUT_NOT_FOUND diagnostic, the same code the CLI reports.

Example client configuration

Most MCP clients accept a JSON config with a command and args. To register the Kubb MCP server over stdio:

mcp.json

{
  "mcpServers": {
    "kubb": {
      "command": "npx",
      "args": ["kubb", "mcp"]
    }
  }
}

See also

• @kubb/mcp, the plugin docs with the full list of tools the MCP server exposes
• Concepts: Plugins: how plugins integrate with the Kubb pipeline