Rails-AI-Context Gem Provides Claude Code with Complete Rails App Model via MCP

What This Is

The rails-ai-context gem addresses Claude Code's limitations with Rails applications by automatically introspecting the entire app and exposing its structure through Model Context Protocol (MCP). This gives Claude Code a complete mental model of the Rails app without manual configuration.

Key Details

The gem solves specific problems where Claude Code "guesses a lot" with Rails: reading thousands of lines in schema.rb to find one column, missing encrypted columns, not knowing Stimulus wiring, and inventing UI patterns instead of matching existing ones.

Setup requires adding to the Gemfile:

gem "rails-ai-context", group: :development

And running the generator:

rails generate rails_ai_context:install

Claude Code automatically discovers the MCP server through a .mcp.json file with zero manual setup.

The gem provides 39 tools that Claude can call directly, including:

• rails_get_schema(table: "users")
• rails_search_code(pattern: "can_cook?", match_type: "trace")
• rails_validate(files: ["app/models/user.rb"])
• rails_analyze_feature(feature: "billing")
• rails_get_stimulus()
• rails_get_turbo_map()

Instead of reading every file, Claude can query exactly what it needs: schema with encrypted and nullable hints, model associations and scopes, route maps, Stimulus controller-to-HTML wiring, Turbo broadcast-to-subscription mapping, and actual design system patterns.

The gem also generates a CLAUDE.md file and .claude/rules/ per-tool split files so Claude has context even without MCP.

There's a CLI fallback where the same 39 tools work as rails 'ai:tool[schema]' for any workflow.

The project is MIT licensed and requires Ruby 3.2+ and Rails 7.1+.

Who It's For

Rails developers using Claude Code who want more accurate, context-aware assistance without manual file reading or configuration.