Add semantic conventions for A2A (Agent-to-Agent) protocol

[xiaocang]

Overview

This proposal adds semantic conventions for the A2A (Agent-to-Agent) protocol, which enables agents from different vendors/frameworks to communicate. A2A uses JSON-RPC 2.0 over HTTP and supports both synchronous and streaming (SSE) responses.

Motivation

A2A is an emerging standard for agent interoperability. As agentic AI systems become more prevalent, observability for agent-to-agent communication is critical. Currently, there are no semantic conventions for A2A, forcing implementations to use vendor-specific namespaces (e.g., kong.a2a.*).

Proposed Attributes

gen_ai.a2a.* namespace

Attribute	Type	Description
gen_ai.a2a.rpc.method	string	JSON-RPC method (e.g., message/send, tasks/get)
gen_ai.a2a.task.id	string	A2A Task ID
gen_ai.a2a.task.state	string	Task state: submitted, working, input-required, completed, failed, canceled
gen_ai.a2a.protocol.version	string	A2A protocol version (e.g., 0.3)
gen_ai.a2a.streaming	boolean	Whether the response uses SSE streaming

Reuse existing gen_ai.* attributes

Attribute	A2A Mapping
gen_ai.operation.name	Operation type (see below)
gen_ai.conversation.id	A2A contextId

Operation name mapping

A2A Endpoint	gen_ai.operation.name
/message/send	invoke_agent
/message/sendStreaming	invoke_agent
/tasks/{id}	get_task
/tasks	list_tasks
/tasks/{id}/cancel	cancel_task
/tasks/{id}/subscribe	stream_task_updates
/agentCard	get_agent_card

A2A Protocol Reference

• Specification: https://a2a-protocol.org/latest/specification/
• GitHub: https://github.com/google/A2A

Related

• GenAI semantic conventions: https://github.com/open-telemetry/semantic-conventions/tree/main/docs/gen-ai