agent-coordinator/docs/MCP_COMPLIANCE_ENHANCEMENTS.md

MCP Compliance Enhancement Summary

Overview

This document summarizes the enhanced Model Context Protocol (MCP) compliance features implemented in the Agent Coordinator system, focusing on session management, security, and real-time streaming capabilities.

Implemented Features

1. 🔐 Enhanced Session Management

Session Token Authentication

• Implementation: Modified register_agent to return cryptographically secure session tokens
• Token Format: 32-byte secure random tokens, Base64 encoded
• Expiry: 60-minute session timeout with automatic cleanup
• Headers: Support for Mcp-Session-Id header (MCP compliant) and X-Session-Id (legacy)

Session Validation Flow

Client                    Server
  |                         |
  |-- POST /mcp/request ---->|
  |    register_agent        |
  |                         |
  |<-- session_token --------|
  |    expires_at            |
  |                         |
  |-- Subsequent requests -->|
  |    Mcp-Session-Id: token |
  |                         |
  |<-- Authenticated resp ---|

Key Components

• SessionManager GenServer: Manages token lifecycle and validation
• Secure token generation: Uses :crypto.strong_rand_bytes/1
• Automatic cleanup: Periodic removal of expired sessions
• Backward compatibility: Supports legacy X-Session-Id headers

2. 📋 MCP Protocol Version Compliance

Protocol Headers

• MCP-Protocol-Version: 2025-06-18 (current specification)
• Server: AgentCoordinator/1.0 identification
• Applied to: All JSON responses via enhanced send_json_response/3

CORS Enhancement

• Session Headers: Added mcp-session-id, mcp-protocol-version to allowed headers
• Exposed Headers: Protocol version and server headers exposed to clients
• Security: Enhanced origin validation with localhost and HTTPS preference

3. 🔒 Security Enhancements

Origin Validation

defp validate_origin(origin) do
  case URI.parse(origin) do
    %URI{host: host} when host in ["localhost", "127.0.0.1", "::1"] -> origin
    %URI{host: host} when is_binary(host) ->
      if String.starts_with?(origin, "https://") or
         String.contains?(host, ["localhost", "127.0.0.1", "dev", "local"]) do
        origin
      else
        Logger.warning("Potentially unsafe origin: #{origin}")
        "*"
      end
    _ -> "*"
  end
end

Authenticated Method Protection

Protected methods requiring valid session tokens:

• agents/register ✓
• agents/unregister ✓
• agents/heartbeat ✓
• tasks/create ✓
• tasks/complete ✓
• codebase/register ✓
• stream/subscribe ✓

4. 📡 Server-Sent Events (SSE) Support

Real-time Streaming Endpoint

• Endpoint: GET /mcp/stream
• Transport: Streamable HTTP (MCP specification)
• Authentication: Requires valid session token
• Content-Type: text/event-stream

SSE Event Format

event: connected
data: {"session_id":"agent_123","protocol_version":"2025-06-18","timestamp":"2025-01-11T..."}

event: heartbeat
data: {"timestamp":"2025-01-11T...","session_id":"agent_123"}

Features

• Connection establishment: Sends initial connected event
• Heartbeat: Periodic keepalive events
• Session tracking: Events include session context
• Graceful disconnection: Handles client disconnects

Technical Implementation Details

File Structure

lib/agent_coordinator/
├── session_manager.ex          # Session token management
├── mcp_server.ex              # Enhanced register_agent
├── http_interface.ex          # HTTP/SSE endpoints + security
└── application.ex             # Supervision tree

Session Manager API

# Create new session
{:ok, session_info} = SessionManager.create_session(agent_id, capabilities)

# Validate existing session
{:ok, session_info} = SessionManager.validate_session(token)
{:error, :expired} = SessionManager.validate_session(old_token)

# Manual cleanup (automatic via timer)
SessionManager.cleanup_expired_sessions()

HTTP Interface Enhancements

# Session validation middleware
case validate_session_for_method(method, conn, context) do
  {:ok, session_info} -> # Process request
  {:error, auth_error} -> # Return 401 Unauthorized
end

# MCP headers on all responses
defp put_mcp_headers(conn) do
  conn
  |> put_resp_header("mcp-protocol-version", "2025-06-18")
  |> put_resp_header("server", "AgentCoordinator/1.0")
end

Usage Examples

1. Agent Registration with Session Token

curl -X POST http://localhost:4000/mcp/request \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": "1",
    "method": "agents/register",
    "params": {
      "name": "My Agent Blue Koala",
      "capabilities": ["coding", "testing"],
      "codebase_id": "my_project"
    }
  }'

# Response:
{
  "jsonrpc": "2.0",
  "id": "1",
  "result": {
    "agent_id": "My Agent Blue Koala",
    "session_token": "abc123...",
    "expires_at": "2025-01-11T15:30:00Z"
  }
}

2. Authenticated Tool Call

curl -X POST http://localhost:4000/mcp/request \
  -H "Content-Type: application/json" \
  -H "Mcp-Session-Id: abc123..." \
  -d '{
    "jsonrpc": "2.0",
    "id": "2",
    "method": "tools/call",
    "params": {
      "name": "get_task_board",
      "arguments": {"agent_id": "My Agent Blue Koala"}
    }
  }'

3. Server-Sent Events Stream

const eventSource = new EventSource('/mcp/stream', {
  headers: {
    'Mcp-Session-Id': 'abc123...'
  }
});

eventSource.onmessage = function(event) {
  const data = JSON.parse(event.data);
  console.log('Received:', data);
};

Testing and Verification

Automated Test Script

• File: test_session_management.exs
• Coverage: Registration flow, session validation, protocol headers
• Usage: elixir test_session_management.exs

Manual Testing

1. Start server: mix phx.server
2. Register agent via /mcp/request
3. Use returned session token for authenticated calls
4. Verify MCP headers in responses
5. Test SSE stream endpoint

Benefits

🔐 Security

• Token-based authentication: Prevents unauthorized access
• Session expiry: Limits exposure of compromised tokens
• Origin validation: Mitigates CSRF and unauthorized origins
• Method-level protection: Granular access control

📋 MCP Compliance

• Official protocol version: Headers indicate MCP 2025-06-18 support
• Streamable HTTP: Real-time capabilities via SSE
• Proper error handling: Standard JSON-RPC error responses
• Session context: Request metadata for debugging

🚀 Developer Experience

• Backward compatibility: Legacy headers still supported
• Clear error messages: Detailed authentication failure reasons
• Real-time updates: Live agent status via SSE
• Easy testing: Comprehensive test utilities

Future Enhancements

Planned Features

• PubSub integration: Event-driven SSE updates
• Session persistence: Redis/database backing
• Rate limiting: Per-session request throttling
• Audit logging: Session activity tracking
• WebSocket upgrade: Bidirectional real-time communication

Configuration Options

• Session timeout: Configurable expiry duration
• Security levels: Strict/permissive origin validation
• Token rotation: Automatic refresh mechanisms
• Multi-tenancy: Workspace-scoped sessions

---

This implementation provides a solid foundation for MCP-compliant session management while maintaining the flexibility to extend with additional features as requirements evolve.