Crate a2a_client 

A2A Protocol Client

This crate provides a client for calling remote A2A (Agent-to-Agent) protocol compliant agents. It supports both streaming and non-streaming interactions over HTTP/HTTPS.

Features

• Full A2A protocol support (JSON-RPC 2.0)
• Non-streaming and streaming message support
• Task retrieval and listing
• Agent discovery via agent cards
• Authentication support (Bearer tokens)
• Error handling with detailed error types

Example

use a2a_client::A2AClient;
use a2a_types::{Message, MessageRole, MessageSendParams, Part};

// Create client from agent card URL
let client = A2AClient::from_card_url("https://agent.example.com")
    .await?
    .with_auth_token("your_api_key");

// Create message
let message = Message {
    kind: "message".to_string(),
    message_id: "msg_123".to_string(),
    role: MessageRole::User,
    parts: vec![Part::Text {
        text: "Hello!".to_string(),
        metadata: None,
    }],
    context_id: None,
    task_id: None,
    reference_task_ids: Vec::new(),
    extensions: Vec::new(),
    metadata: None,
};

// Send message
let params = MessageSendParams {
    message,
    configuration: None,
    metadata: None,
};

let result = client.send_message(params).await?;

Re-exports

pub use client::A2AClient;

pub use error::A2AError;

pub use error::A2AResult;

Modules

client

A2A Client for calling remote A2A agents

constants

Constants for the A2A client

error

Error types for A2A client operations