Agent-to-Agent (A2A) server in Elastic Agent Builder
Elastic Cloud Serverless projects are autoscaled environments, fully managed by Elastic and available on Elastic Cloud. Availability This functionality is generally available and ready for production usage. Elastic Cloud Serverless projects are autoscaled environments, fully managed by Elastic and available on Elastic Cloud. Availability This functionality is generally available and ready for production usage. Elastic Cloud Serverless projects are autoscaled environments, fully managed by Elastic and available on Elastic Cloud. Availability This functionality is generally available and ready for production usage. The Elastic Stack includes Elastic's core products such as Elasticsearch, Kibana, Logstash, and Beats. Availability This functionality is generally available and ready for production usage. This functionality is in technical preview and is ready for evaluation. Use with caution in production; it is not recommended for mission-critical workloads. Elastic will work to fix any issues, but features in technical preview are not subject to the support SLA of official GA features. Specific Support terms apply. Unless stated otherwise on the page, this functionality is available when your Elastic Stack is deployed on Elastic Cloud Hosted, Elastic Cloud Enterprise, Elastic Cloud on Kubernetes, and self-managed environments. This documentation corresponds to the latest patch available for each minor version. If you're not using the latest patch, check the release notes for changes.
Serverless Elasticsearch
Generally available
Serverless Observability
Generally available
Serverless Security
Generally available
Stack
GA
9.3+
…
Generally available since 9.3
Preview in 9.2
The Agent-to-Agent (A2A) server enables external A2A clients, such as other agent frameworks, to communicate with Elastic Agent Builder agents.
Returns the agent card for a specific agent. The agent card is the agent's metadata, including its capabilities. The agentId is a path parameter that corresponds to your agent IDs:
GET /api/agent_builder/a2a/{agentId}.json
Interact with agents following the A2A protocol specification:
POST /api/agent_builder/a2a/{agentId}
Both A2A endpoints require API key authentication. Refer to Create a read-only client key for a limited key example. For more information about the A2A protocol, refer to the A2A protocol specification.
By default, message/send waits until the agent finishes, then returns the complete agent message in a single response.
In 9.2 through 9.5, message/stream isn't supported. Refer to Limitations and known issues.
Elastic Cloud Serverless projects are autoscaled environments, fully managed by Elastic and available on Elastic Cloud. Availability This functionality is generally available and ready for production usage. Serverless interfaces and procedures might differ from classic Elastic Stack deployments. The Elastic Stack includes Elastic's core products such as Elasticsearch, Kibana, Logstash, and Beats. Availability This functionality is generally available and ready for production usage. Unless stated otherwise on the page, this functionality is available when your Elastic Stack is deployed on Elastic Cloud Hosted, Elastic Cloud Enterprise, Elastic Cloud on Kubernetes, and self-managed environments. This documentation corresponds to the latest patch available for each minor version. If you're not using the latest patch, check the release notes for changes.
Serverless
Generally available
Stack
9.4+
Generally available since 9.4
In 9.4, non-blocking requests require version 9.4.5 or later. On earlier versions, configuration.blocking: false is ignored and the request waits for the complete response.
To get a response without waiting for the agent to finish, call message/send with configuration.blocking set to false. The response is a task. Poll it with tasks/get until it reaches a final state, then read status.message, which contains the agent's response or, if the task failed, the error. For the task states, refer to the A2A protocol specification.
Elastic Cloud Serverless projects are autoscaled environments, fully managed by Elastic and available on Elastic Cloud. Availability This functionality is generally available and ready for production usage. Serverless interfaces and procedures might differ from classic Elastic Stack deployments. The Elastic Stack includes Elastic's core products such as Elasticsearch, Kibana, Logstash, and Beats. Availability We plan to add this functionality in a future Elastic Stack update. Subject to changes. Unless stated otherwise on the page, this functionality is available when your Elastic Stack is deployed on Elastic Cloud Hosted, Elastic Cloud Enterprise, Elastic Cloud on Kubernetes, and self-managed environments. This documentation corresponds to the latest patch available for each minor version. If you're not using the latest patch, check the release notes for changes.
Serverless
Generally available
Stack
Planned
Planned
Call the message/stream method to receive the response as a stream of server-sent events. The agent card reports streaming support by setting capabilities.streaming to true.
The stream uses the A2A streaming events. Artifact updates contain the agent's response text, and status updates in the working state report progress, such as tool calls. The final status update is completed, failed, or input-required.
The input-required state means the agent is waiting for a response to a prompt, which A2A clients can't send. Refer to Human-in-the-loop prompts require an interactive conversation.
If the client disconnects before the stream ends, the agent stops.