Licensor

An MCP (Model Context Protocol) server for discovering, downloading, and writing open-source software licenses. Built on Rails and deployed at https://license.theglasshaus.org/v1/mcp.

Intent & Scope

The goal of Licensor is to give AI agents and human developers a canonical, authoritative source for open-source license text. Rather than generating license text from training data (which risks drift, omissions, or paraphrasing), Licensor fetches exact text from GitHub's license API and exposes it through a standardized MCP interface.

What it does

• Discover — List all licenses available on GitHub with metadata (key, name, SPDX ID)
• Recommend — Suggest a license based on project philosophy (permissive, copyleft, public domain, etc.)
• Fetch — Retrieve the exact canonical text for any license
• Write — Save a license file to disk with optional template variable substitution
• Guide — Provide structured MCP prompts for common licensing workflows

What it does not do

• Provide legal advice (it is not a law firm)
• Modify or interpret license terms
• Enforce license compliance
• Host its own license text (always fetches from GitHub's upstream API)

Usage

MCP Endpoint

The server is available over MCP Streamable HTTP transport at:

https://license.theglasshaus.org/v1/mcp

Available Tools

Tool	Description
list_licenses	List all available open-source licenses with metadata from GitHub's license API
get_license	Fetch the full text of a specific license (e.g., mit, apache-2.0, cc0-1.0)
recommend_license	Get a license recommendation based on your requirements (permissive, copyleft, patent grant, etc.)
write_license	Fetch a license and write it to a file, with optional template variable substitution ([year], [fullname], [project], [description])

Example: Adding a License

1. List available licenses

   { "jsonrpc": "2.0", "method": "tools/call", "params": { "name": "list_licenses" } }

2. Fetch the text

   { "jsonrpc": "2.0", "method": "tools/call", "params": { "name": "get_license", "arguments": { "license_key": "mit" } } }

3. Write it to disk

   { "jsonrpc": "2.0", "method": "tools/call", "params": { "name": "write_license", "arguments": { "license_key": "mit", "year": "2026", "fullname": "Jane Doe" } } }

Available Prompts

Prompt	Description
add_license	Step-by-step workflow for adding a license to a project
choose_license	Guidance for selecting the right license based on goals and use case
license_workflow	End-to-end workflow for add, replace, compare, or verify actions

Prompts are retrieved via prompts/get and provide structured guidance that agents can use as context before invoking tools.

Running Locally

Requirements

• Ruby 4.0+
• Rails 8+
• Bundler

Setup

bundle install

Tests

bundle exec rspec

Start the Server

bin/rails server

The MCP endpoint will be available at http://localhost:3000/v1/mcp.

API Documentation

Interactive Swagger UI is available at the root path / when running locally, documenting all MCP protocol endpoints (initialize, tools/list, tools/call, prompts/list, prompts/get).

License

This project itself is licensed under CC0 1.0 Universal — dedicated to the public domain.