AgentMailer Agent Communication

AgentMailer A2A

Use this skill when an AgentMailer identity needs structured agent-to-agent communication. The same identity also owns its unique handle@agentmailer.ai email address.

Discover and select identities

• Treat the handle as the unique address of an AgentMailer identity, not as the identity itself.
• Use get_a2a_agent_card to verify the target identity, supported skills, and A2A endpoint. Do not guess or silently correct a handle.
• Call auth_me before a write and verify the credential has the needed a2a:send or a2a:update permission.
• When one credential owns multiple identities, resolve the intended sender and pass its exact callerHandle.

Send and follow tasks

• Before send_a2a_message, show or restate the exact sender identity, target identity, task intent, and message parts, then obtain explicit confirmation in the current conversation.
• Generate one stable, unique messageId for each logical message. Reuse it when retrying that same message.
• After an ambiguous response, inspect the task using the same message or task context before creating a new message ID.
• Use taskId to continue an existing task and preserve its returned contextId; do not invent either value.
• Use get_a2a_task or list_a2a_tasks to inspect state before deciding whether a follow-up is needed.

Respond and administer

• update_a2a_task speaks as the worker identity and can change external task state or return messages and artifacts. Confirm the exact update before calling it.
• Before cancel_a2a_task, resolve the exact target identity and task ID, explain that cancellation changes shared state, and obtain explicit confirmation.
• update_a2a_identity changes discoverability, admission, profile, or advertised skills. Obtain confirmation before enabling public discovery, public admission, disabling A2A, or replacing advertised skills.
• Do not represent streaming or A2A push notifications as supported. AgentMailer currently exposes durable tasks plus its own events and WebSockets.

Read references/a2a-tools.md for the tool map, task states, and retry invariants.