Class: Otto::MCP::Protocol

Inherits:
Object
  • Object
show all
Defined in:
lib/otto/mcp/protocol.rb

Overview

MCP protocol handler providing Model Context Protocol functionality.

JSON-RPC error code to HTTP status mapping

Code     Meaning                 HTTP
-32700   Parse error             400
-32600   Invalid Request         400
-32601   Method not found        400
-32602   Invalid params          400
-32001   Resource not found      404
-32002   Tool not found          404
-32603   Internal error          500
-32099..-32000  server errors    500

Protocol-level faults (a malformed or unsupported payload against a valid endpoint) are 400, including method-not-found: 404 there would conflate a bad payload with "no such route", which the MCP endpoint handler already returns when MCP is disabled. 404 is reserved for a well-formed request naming an entity that is not registered, and 500 for handler execution faults. Handler exception messages are logged, never returned: -32603 responses carry a fixed message.

Constant Summary collapse

ERROR_STATUS_MAP =

See Also:

{
  -32_700 => 400, # Parse error
  -32_600 => 400, # Invalid Request
  -32_601 => 400, # Method not found
  -32_602 => 400, # Invalid params
  -32_001 => 404, # Resource not found
  -32_002 => 404, # Tool not found
  -32_603 => 500, # Internal error
}.freeze
SERVER_ERROR_RANGE =

Implementation-defined server error range; anything unmapped inside it is an execution fault.

(-32_099..-32_000)

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(otto_instance) ⇒ Protocol

Returns a new instance of Protocol.



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# File 'lib/otto/mcp/protocol.rb', line 50

def initialize(otto_instance)
  @otto     = otto_instance
  @registry = Registry.new
end

Instance Attribute Details

#registry ⇒ Object (readonly)

Returns the value of attribute registry.



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# File 'lib/otto/mcp/protocol.rb', line 48

def registry
  @registry
end

Instance Method Details

#handle_request(env) ⇒ Object 



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# File 'lib/otto/mcp/protocol.rb', line 55

def handle_request(env)
  request = @otto.request_class.new(env)

  unless request.post? && request.content_type&.include?('application/json')
    return error_response(nil, -32_600, 'Invalid Request', 'Only JSON-RPC POST requests supported')
  end

  begin
    body = request.body.read
    data = JSON.parse(body)
  rescue JSON::ParserError
    return error_response(nil, -32_700, 'Parse error', 'Invalid JSON')
  end

  unless valid_jsonrpc_request?(data)
    return error_response(data['id'], -32_600, 'Invalid Request', 'Missing jsonrpc, method, or id fields')
  end

  case data['method']
  when 'initialize'
    handle_initialize(data)
  when 'resources/list'
    handle_resources_list(data)
  when 'resources/read'
    handle_resources_read(data)
  when 'tools/list'
    handle_tools_list(data)
  when 'tools/call'
    handle_tools_call(data, env)
  else
    error_response(data['id'], -32_601, 'Method not found', "Unknown method: #{data['method']}")
  end
end