Cancel a running A2A task.

This tool requests cancellation of an active task. The agent will attempt to gracefully stop the task execution and update its status to "canceled".

Args:

• agentCardUrl (string): URL to the agent's card endpoint

• taskId (string): The unique identifier of the task to cancel

Returns: JSON response confirming the cancellation request:

• success: Boolean indicating if cancellation was initiated

• message: Description of the cancellation result

• task: Updated task object with "canceled" status (if available)

Note: Cancellation may not be immediate. The task status should transition to "canceled" once the agent completes the cancellation process.

Examples:

• Use when: "Cancel the long-running task abc-123" params: { agentCardUrl: "https://agent.example.com/.well-known/agent-card.json", taskId: "abc-123" }

• Use when: "Stop the data processing task I started" params: { agentCardUrl: "https://agent.example.com/.well-known/agent-card.json", taskId: "task-id-to-cancel" }

• Don't use when: Task has already completed (cancellation only works for active tasks)

Error Handling:

• Returns "Error: Task not found" if the task ID doesn't exist

• Returns "Error: Task already completed" if the task is no longer running

• Returns "Error: Cancellation not supported" if the agent doesn't support task cancellation

• After cancellation, use a2a_get_task to verify the task status changed to "canceled"

Retrieve an agent's card containing metadata and capability information.

This tool fetches the agent card which describes what the agent can do, its configuration, supported features, and other metadata.

Args:

• agentCardUrl (string): URL to the agent's card endpoint, typically at /.well-known/agent-card.json

Returns: JSON response containing the agent card with:

• name: Agent name

• description: Agent purpose and capabilities

• version: Agent version

• skills: Array of skills/capabilities the agent provides

• endpoints: Available API endpoints

• supportedFeatures: List of A2A protocol features supported

• metadata: Additional agent information

Agent cards follow the A2A protocol specification and help clients understand how to interact with the agent.

Examples:

• Use when: "What can this agent do?" params: { agentCardUrl: "https://agent.example.com/.well-known/agent-card.json" }

• Use when: "Get information about the weather agent's capabilities" params: { agentCardUrl: "https://weather-agent.example.com/.well-known/agent-card.json" }

• Use when: "I need to know what features this agent supports before sending a message" params: { agentCardUrl: "https://agent.example.com/.well-known/agent-card.json" }

• Don't use when: You want to send a message (use a2a_send_message instead)

Error Handling:

• Returns "Error: Failed to fetch agent card" if the URL is unreachable

• Returns "Error: Invalid agent card format" if the card doesn't conform to A2A specifications

• Returns "Error: Agent card not found" if the endpoint returns 404

Retrieve the status and details of an A2A task by its ID.

This tool fetches information about a previously created task, including its current status, progress, and any generated artifacts.

Args:

• agentCardUrl (string): URL to the agent's card endpoint

• taskId (string): The unique identifier of the task to retrieve

Returns: JSON response containing task information:

• id: Task identifier

• status: Object with state ("submitted", "in_progress", "completed", "failed", "canceled") and optional progress information

• artifacts: Array of generated outputs, each with:

  • artifactId: Unique identifier

  • name: Artifact name/title

  • kind: Type of artifact (e.g., "text", "image", "file")

  • parts: Artifact content

• messages: Conversation history associated with the task

• created: Task creation timestamp

• updated: Last update timestamp

Examples:

• Use when: "Check the status of task xyz-789" params: { agentCardUrl: "https://agent.example.com/.well-known/agent-card.json", taskId: "xyz-789" }

• Use when: "Get the results from the task I started earlier" params: { agentCardUrl: "https://agent.example.com/.well-known/agent-card.json", taskId: "previously-returned-task-id" }

• Don't use when: You want to send a new message (use a2a_send_message instead)

Error Handling:

• Returns "Error: Task not found" if the task ID doesn't exist

• Returns "Error: Failed to connect to agent" if the agent is unreachable

• Task status will indicate "failed" if the task encountered errors during execution

Send a message to an Agent-to-Agent (A2A) protocol compliant agent.

This tool establishes communication with an A2A agent and sends a text message. The agent may respond immediately with a message or return a task object for asynchronous processing.

Args:

• agentCardUrl (string): URL to the agent's card endpoint, typically at /.well-known/agent-card.json

• message (string): The text message to send to the agent (1-10,000 characters)

• taskId (string, optional): Existing task ID to continue a conversation thread. If provided, the message is sent as a follow-up to the specified task.

Returns: JSON response containing either:

• A message object with the agent's immediate response

• A task object for asynchronous operations, containing:

  • id: Task identifier

  • status: Current task state and progress

  • artifacts: Any generated outputs or results

  • kind: Response type ("message" or "task")

The response may include multiple parts (text, images, etc.) depending on the agent's capabilities.

Examples:

• Use when: "Ask the weather agent what the forecast is for tomorrow" params: { agentCardUrl: "https://weather-agent.example.com/.well-known/agent-card.json", message: "What's tomorrow's forecast?" }

• Use when: "Continue the conversation with task abc-123" params: { agentCardUrl: "https://agent.example.com/.well-known/agent-card.json", message: "Thanks, can you be more specific?", taskId: "abc-123" }

• Don't use when: You need to cancel a task (use a2a_cancel_task instead)

• Don't use when: You need to check task status (use a2a_get_task instead)

Error Handling:

• Returns "Error: Failed to connect to agent" if the agent URL is unreachable

• Returns "Error: Invalid agent card" if the card endpoint doesn't return valid A2A metadata

• Returns "Error: Message sending failed" if the agent rejects the message

• If a task is returned, use a2a_get_task to poll for completion status