Action MCP

bundle add actionmcp
bundle install
bin/rails action_mcp:install:migrations
bin/rails generate action_mcp:install
bin/rails db:migrate

# config/application.rb
config.action_mcp.name = "My Rails MCP Server"
config.action_mcp.version = "1.0.0"
config.action_mcp.logging_enabled = true
config.action_mcp.logging_level = :info

bin/rails generate action_mcp:tool SearchProducts

# app/mcp/tools/search_products_tool.rb
class SearchProductsTool < ApplicationMCPTool
  tool_name "search_products"
  description "Search the product catalog by keyword"
  property :query, type: "string", required: true
  def perform
    results = Product.search(query)
    render(text: results.map(&:name).join(", "))
  end
end

# app/mcp/application_gateway.rb
class ApplicationGateway < ActionMCP::Gateway
  identified_by :user
  def authenticate!
    token = extract_bearer_token
    user = User.find_by(api_token: token)
    raise ActionMCP::Unauthorized unless user
    { user: user }
  end
end

# Development
bin/mcp

# Or explicitly with Puma on port 62770
bundle exec rails s -c mcp/config.ru -p 62770

{
  "mcpServers": {
    "my-rails-app": {
      "url": "http://localhost:62770/mcp",
      "headers": {
        "Authorization": "Bearer your-api-token"
      }
    }
  }
}