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A2A Client Tool

Tool for sending data to A2A (Agent-to-Agent) servers for processing
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Overview

The A2A Client Tool node enables sending data to Agent-to-Agent (A2A) servers for processing tasks. It is designed to integrate with an A2A registry to discover available agent servers or allows manual entry of a server URL. The node submits tasks describing what should be done with the input data, optionally waits for synchronous completion or returns immediately in asynchronous mode.

This node is beneficial when you want to offload specific data processing or automation tasks to external A2A agents that can perform specialized operations. For example, it can be used to send JSON data to an AI agent for analysis, trigger workflow automation on a remote agent, or delegate complex computations to distributed services.

Practical examples:

  • Sending customer data to an external agent for enrichment or validation.
  • Submitting image metadata to an AI agent for tagging or classification.
  • Dispatching log data to a monitoring agent for anomaly detection.

Properties

Name Meaning
A2A Registry URL URL of the A2A registry used to discover available agent servers.
A2A Server Select an A2A server from the discovered registry list or choose manual entry to specify URL.
Manual Server URL When manual entry is selected, enter the full URL of the A2A server here.
Task Type Type/category of the task to execute on the A2A agent (e.g., "data_processing").
Task Description Text description explaining what the A2A agent should do with the data.
Message Human-readable instruction or message sent to the A2A agent to guide processing.
Processing Mode How to process the task: "Synchronous" waits for completion; "Asynchronous" submits and returns immediately.
Timeout (seconds) Maximum time to wait for the A2A server response before timing out (in seconds).

Output

The node outputs JSON data for each input item enriched with the following fields:

  • a2a_result: The result object returned by the A2A agent after processing the task.
  • a2a_task_id: Unique identifier generated for the submitted task.
  • a2a_server: The URL of the A2A server that processed the task.
  • a2a_registry: The URL of the A2A registry used for discovery.
  • a2a_task_type: The type of task executed.
  • a2a_task_description: Description of the task sent to the agent.
  • a2a_message: The human-readable message sent to the agent.
  • a2a_success: Boolean indicating if the task was successfully processed.
  • a2a_processed_at: Timestamp when the task was processed.
  • result: Alias for a2a_result.
  • success: Alias for a2a_success.
  • processed_at: Alias for a2a_processed_at.

In case of failure, the output includes:

  • a2a_success: false
  • a2a_error: Error message describing the failure.
  • a2a_failed_at: Timestamp of failure.
  • success: false
  • error: Error message.
  • failed_at: Timestamp of failure.

The node does not output binary data.

Dependencies

  • Requires access to an A2A registry service URL to discover agent servers (optional but recommended).
  • Requires connectivity to the selected A2A server endpoint.
  • Uses HTTP POST requests with JSON-RPC 2.0 protocol to communicate with A2A servers.
  • Supports setting request timeout via node property.
  • No internal credential types are required, but network access and possibly authentication headers may be needed depending on the A2A server configuration.

Troubleshooting

  • Invalid Server Selection: Selecting invalid options like "none", "registry_error", or "separator" as the A2A server will cause errors. Ensure a valid server or manual URL is provided.
  • Manual Server URL Missing: If "manual" is selected for the server, the manual server URL must be entered; otherwise, an error is thrown.
  • Timeouts: Requests may fail if the A2A server does not respond within the configured timeout period.
  • Registry Connection Issues: Failure to connect to the registry results in fallback to predefined local servers and a warning option in the server selection list.
  • Server Response Errors: If the A2A server responds with an error status or JSON-RPC error, the node throws an error with the server's message.
  • Network Issues: Ensure network connectivity and correct URLs for both registry and A2A servers.

Links and References

  • JSON-RPC 2.0 Specification
  • Documentation or API reference for your specific A2A registry and agent servers (not included in source code).

Discussion