Send a message to another agent. Supports deduplication and threading.

Read unread messages for an agent. Messages are marked as delivered.

Send a message to all registered agents.

Search messages by content, subject, or sender/recipient.

Send a message and wait for a reply (synchronous request/reply pattern with polling).

List conversation threads for an agent.

Count messages by status for an agent.

Register an agent in the mailbox system with a name, role, and optional A2A Agent Card metadata.

List all registered agents with their roles and last activity.

Get recent messaging activity feed.

Submit a task to another agent via the A2A protocol. Creates a new task with an initial message.

Get the status and full history of an A2A task including messages and artifacts.

Cancel an A2A task. Only non-terminal tasks can be canceled.

List A2A tasks for an agent with pagination.

Respond to an A2A task as the assigned agent. Sends a response and optionally updates the task status.

Acquire an advisory lease on a resource. Used for coordinating exclusive or shared access between agents.

Release a previously acquired resource lease.

Check the current lease status of a resource.

List messages in the dead-letter queue. These are messages that expired or failed delivery.

Retry a dead-letter message by re-inserting it as a new pending message.

Remove all entries from the dead-letter queue.