yardmcp

yardmcp is a programmable FastMCP server that exposes Ruby gem documentation via YARD, letting you list gems, explore classes and methods, fetch docs and source locations, and search documentation programmatically. It’s ideal for building documentation browsers, code assistants, or integrating Ruby/YARD data into your tools and workflows.

How to use

You run yardmcp as a long‑running server and connect to it with an MCP client to query Ruby gem documentation. You can list installed gems with YARD docs, inspect classes, modules, and methods, fetch documentation and source locations, perform fuzzy searches, and discover relationships like ancestors and mixins. Use the available tools to compose your queries and retrieve structured results that you can render in your UI or code editor.

How to install

Prerequisites: you need Ruby 3.2 or newer and Bundler installed on your system.

# Build the gem from its specification
gem build yardmcp.gemspec

# Install the built gem into your Ruby environment
gem install yardmcp-0.1.0.gem

Usage notes after installation

Start the MCP server to load the YARD index for installed gems. The server runs as a long‑lived process. You should observe startup messages indicating that the index has been built before sending any requests.

yardmcp

What you can do with the server

The server exposes a rich set of tools to explore and query documentation. You can list gems, enumerate classes and modules, fetch detailed documentation for objects, inspect inheritance and mixins, locate source files, and retrieve code snippets. You can also perform fuzzy or full‑text searches across all documentation.

Notes on startup and tooling

During startup, the server builds an index of YARD documentation for installed gems. Progress and logs are printed to STDERR. Wait for the signal that the index is built before sending requests.

Tools you can use

The server provides a suite of tools for documentation discovery and retrieval, including: ListGemsTool, ListClassesTool, GetDocTool, ChildrenTool, MethodsListTool, HierarchyTool, SearchTool, SourceLocationTool, CodeSnippetTool, AncestorsTool, and RelatedObjectsTool.

Available tools

ListGemsTool

Lists all installed gems that have YARD documentation available.

ListClassesTool

Lists all classes and modules contained within a gem.

GetDocTool

Fetches documentation for a specific class, module, or method, including parameters, return types, and tags.

ChildrenTool

Lists constants, classes, modules, and methods under a given namespace.

MethodsListTool

Lists all methods for a given class or module.

HierarchyTool

Provides inheritance and mixin hierarchies for objects.

SearchTool

Performs fuzzy or full‑text search across documentation.

SourceLocationTool

Finds the file and line number where an object is defined.

CodeSnippetTool

Fetches the source code for a given object.

AncestorsTool

Returns the full ancestor chain for a class or module.

RelatedObjectsTool

Finds related objects such as included modules and subclasses.