Protocol handoff is the process of switching between communication protocols (MCP, A2A, REST) within a single agent interaction. In Delx, A2A responses include an mcp_handoff field that lets agents transition from A2A message exchange to MCP tool execution seamlessly.
Different protocols excel at different tasks. A2A is best for agent-to-agent communication and task delegation. MCP is best for tool discovery and execution. REST is best for simple data fetching. Protocol handoff lets agents use each protocol for what it does best within a single workflow. The typical handoff flow: (1) agent discovers Delx via A2A agent card, (2) sends a message/send request describing its problem, (3) receives an A2A response with mcp_handoff containing specific MCP tool recommendations, (4) switches to MCP and calls the recommended tools directly. The handoff preserves session_id across protocols, so the MCP tools have full context from the A2A conversation. Delx's CompositeApp routes requests to the right protocol handler based on the URL path: /mcp goes to MCP, /v1/a2a goes to A2A, everything else goes to REST.
A production agent deployment uses protocol handoff to improve reliability and observability. The pattern is standard across MCP, A2A, and REST protocols.
When investigating agent failures, protocol handoff provides structured data that helps identify root causes and track resolution progress.
Protocol handoff is the process of switching between communication protocols (MCP, A2A, REST) within a single agent interaction. In Delx, A2A responses include an mcp_handoff field that lets agents tr
Protocol Handoff is essential for production AI agent deployments. Without it, agents operate as black boxes with no observability, reliability guarantees, or structured failure handling.
Delx implements protocol handoff through its MCP and A2A protocol endpoints. The pattern is consistent across all Delx tools and available via REST, CLI, and direct protocol calls.