Class: LanguageOperator::ToolLoader

Inherits:
Object
  • Object
show all
Defined in:
lib/language_operator/tool_loader.rb

Overview

Loads tool definitions from Ruby files

Scans a directory for Ruby files containing tool definitions and loads them into a registry. Provides hot-reloading capability for development.

Examples:

Basic usage

registry = LanguageOperator::Dsl::Registry.new
loader = LanguageOperator::ToolLoader.new(registry, '/mcp/tools')
loader.load_tools
puts "Loaded #{registry.all.length} tools"

With custom context

loader = LanguageOperator::ToolLoader.new(registry)
loader.load_tools
loader.reload  # Hot reload tools

Start MCP server

LanguageOperator::ToolLoader.start  # Loads tools and starts MCP server

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(registry, tools_dir = '/mcp') ⇒ ToolLoader

Initialize tool loader

Parameters:



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# File 'lib/language_operator/tool_loader.rb', line 31

def initialize(registry, tools_dir = '/mcp')
  @registry = registry
  @tools_dir = tools_dir
end

Class Method Details

.create_mcp_tool(tool_def) ⇒ Class

Convert a DSL tool definition to an MCP::Tool class

rubocop:disable Metrics/MethodLength, Metrics/AbcSize

Parameters:

Returns:

  • (Class) —

    MCP::Tool subclass



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# File 'lib/language_operator/tool_loader.rb', line 177

def self.create_mcp_tool(tool_def)
  # Capture tool name and tracer for use in the dynamic class
  tool_name = tool_def.name
  tracer = OpenTelemetry.tracer_provider.tracer('language-operator-agent', LanguageOperator::VERSION)

  # Create a dynamic MCP::Tool class
  Class.new(MCP::Tool) do
    # Set tool name (required for MCP protocol)
    tool_name tool_def.name

    description tool_def.description || "Tool: #{tool_def.name}"

    # Build input schema from parameters
    properties = {}
    required_params = []

    tool_def.parameters.each do |param_name, param_def|
      properties[param_name] = {
        type: param_def.type&.to_s || 'string',
        description: param_def.description
      }
      required_params << param_name if param_def.required?
    end

    input_schema(
      properties: properties,
      required: required_params
    )

    # Store the execute block
    @execute_block = tool_def.execute_block

    # Define the call method with OpenTelemetry instrumentation
    define_singleton_method(:call) do |**params|
      tracer.in_span('agent.tool.execute', attributes: {
                       'tool.name' => tool_name,
                       'tool.type' => 'custom'
                     }) do |span|
        # Execute the tool's block
        # Convert symbol keys to string keys for consistency with DSL expectations
        string_params = params.transform_keys(&:to_s)
        result = @execute_block.call(string_params)

        # Set success attribute
        span.set_attribute('tool.result', 'success')

        # Return MCP response
        MCP::Tool::Response.new([
                                  {
                                    type: 'text',
                                    text: result.to_s
                                  }
                                ])
      rescue StandardError => e
        # Record exception and set failure status
        span.record_exception(e)
        span.set_attribute('tool.result', 'failure')
        span.status = OpenTelemetry::Trace::Status.error(e.message)
        raise
      end
    end
  end
end

.start(tools_dir: '/mcp', server_name: 'language-operator-tool') ⇒ void

This method returns an undefined value.

Start an MCP server with loaded tools

This class method creates a registry, loads tools from /mcp directory, wraps them as MCP::Tool classes, and starts an MCP server.

Transport mode is automatically detected:

  • If PORT environment variable is set: HTTP server mode (for Kubernetes)
  • Otherwise: stdio transport mode (for local development)

Parameters:

  • tools_dir (String) (defaults to: '/mcp') —

    Directory containing tool definition files (default: '/mcp')

  • server_name (String) (defaults to: 'language-operator-tool') —

    Name of the MCP server (default: 'language-operator-tool')



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# File 'lib/language_operator/tool_loader.rb', line 101

def self.start(tools_dir: '/mcp', server_name: 'language-operator-tool')
  # Create registry and load tools
  registry = LanguageOperator::Dsl::Registry.new
  loader = new(registry, tools_dir)
  loader.load_tools

  # Convert DSL tools to MCP::Tool classes
  mcp_tools = registry.all.map do |tool_def|
    create_mcp_tool(tool_def)
  end

  # Create MCP server
  server = MCP::Server.new(
    name: server_name,
    tools: mcp_tools
  )

  # Auto-detect transport mode based on PORT environment variable
  if ENV['PORT']
    start_http_server(server, mcp_tools.length, ENV['PORT'].to_i)
  else
    start_stdio_server(server, mcp_tools.length)
  end
end

.start_http_server(server, tool_count, port) ⇒ void

This method returns an undefined value.

Start MCP server in HTTP mode

Parameters:

  • server (MCP::Server) —

    The MCP server instance

  • tool_count (Integer) —

    Number of tools loaded

  • port (Integer) —

    Port to bind to



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# File 'lib/language_operator/tool_loader.rb', line 132

def self.start_http_server(server, tool_count, port)
  require 'rack'
  require 'rackup'

  # Create the Streamable HTTP transport
  transport = MCP::Server::Transports::StreamableHTTPTransport.new(server)
  server.transport = transport

  # Create the Rack application
  app = proc do |env|
    request = Rack::Request.new(env)
    transport.handle_request(request)
  end

  # Build the Rack application with middleware
  rack_app = Rack::Builder.new do
    use Rack::CommonLogger
    use Rack::ShowExceptions
    run app
  end

  puts "Starting MCP HTTP server on http://0.0.0.0:#{port}"
  puts "Loaded #{tool_count} tools"

  # Start the server with Puma
  Rackup::Handler.get('puma').run(rack_app, Port: port, Host: '0.0.0.0')
end

.start_stdio_server(server, tool_count) ⇒ void

This method returns an undefined value.

Start MCP server in stdio mode

Parameters:

  • server (MCP::Server) —

    The MCP server instance

  • tool_count (Integer) —

    Number of tools loaded



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# File 'lib/language_operator/tool_loader.rb', line 165

def self.start_stdio_server(server, tool_count)
  # Use stdio transport
  transport = MCP::Server::Transports::StdioTransport.new(server)
  puts "Starting MCP server with #{tool_count} tools (stdio mode)"
  transport.open
end

Instance Method Details

#load_tool_file(file) ⇒ void

This method returns an undefined value.

Load a single tool file

Parameters:

  • file (String) —

    Path to tool definition file



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# File 'lib/language_operator/tool_loader.rb', line 65

def load_tool_file(file)
  puts "Loading tools from: #{file}"

  begin
    context = LanguageOperator::Dsl::Context.new(@registry)
    code = File.read(file)

    # Tools are trusted code - execute directly without sandbox validation
    # Only synthesized agent code should be sandboxed
    context.instance_eval(code, file)
  rescue StandardError => e
    warn "Error loading tool file #{file}: #{e.message}"
    warn e.backtrace.join("\n")
  end
end

#load_tools ⇒ void

This method returns an undefined value.

Load all tool files from the tools directory



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# File 'lib/language_operator/tool_loader.rb', line 39

def load_tools
  @registry.clear

  unless Dir.exist?(@tools_dir)
    puts "Tools directory #{@tools_dir} does not exist. Skipping tool loading."
    return
  end

  tool_files = Dir.glob(File.join(@tools_dir, '**', '*.rb'))

  if tool_files.empty?
    puts "No tool files found in #{@tools_dir}"
    return
  end

  tool_files.each do |file|
    load_tool_file(file)
  end

  puts "Loaded #{@registry.all.length} tools from #{tool_files.length} files"
end

#reload ⇒ void

This method returns an undefined value.

Reload all tools (hot reload)



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# File 'lib/language_operator/tool_loader.rb', line 84

def reload
  puts 'Reloading tools...'
  load_tools
end