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A2A Python SDK — Samples

This directory contains runnable examples demonstrating how to build and interact with an A2A-compliant agent using the Python SDK.

Contents

File Role Description
hello_world_agent.py Server A2A agent server
cli.py Client Interactive terminal client
text_client_cli.py Client Simplified text-only interactive terminal client

All three samples are designed to work together out of the box: the agent listens on http://127.0.0.1:41241, which is the default URL used by both clients.

hello_world_agent.py — Agent Server

Implements an A2A agent that responds to simple greeting messages (e.g., "hello", "how are you", "bye") with text replies, simulating a 1-second processing delay.

Demonstrates:

  • Subclassing AgentExecutor and implementing execute() / cancel()
  • Publishing streaming status updates and artifacts via TaskUpdater
  • Exposing all three transports in both protocol versions (v1.0 and v0.3 compat) simultaneously:
    • JSON-RPC (v1.0 and v0.3) at http://127.0.0.1:41241/a2a/jsonrpc
    • HTTP+JSON (REST) (v1.0 and v0.3) at http://127.0.0.1:41241/a2a/rest
    • gRPC v1.0 on port 50051
    • gRPC v0.3 (compat) on port 50052
  • Serving the agent card at http://127.0.0.1:41241/.well-known/agent-card.json

Run:

uv run python samples/hello_world_agent.py

cli.py — Client

An interactive terminal client with full visibility into the streaming event flow. Each TaskStatusUpdate and TaskArtifactUpdate event is printed as it arrives.

Features:

  • Transport selection via --transport flag (JSONRPC, HTTP+JSON, GRPC)
  • Session management (context_id persisted across messages, task_id per task)
  • Graceful error handling for HTTP and gRPC failures

Run:

# Connect to the local hello_world_agent (default):
uv run python samples/cli.py

# Connect to a different URL, using gRPC:
uv run python samples/cli.py --url http://192.168.1.10:41241 --transport GRPC

Type /quit or /exit to stop, or press Ctrl+C.

text_client_cli.py — Simple Text Client

A stripped-down interactive client using the high-level TextClient abstraction. It hides all streaming and event mechanics, presenting a simple request/response interface.

Ideal for understanding the minimum code required to call an A2A agent.

Run:

# Connect to the local hello_world_agent (default):
uv run python samples/text_client_cli.py

# Connect to a different URL:
uv run python samples/text_client_cli.py --url http://192.168.1.10:41241

# Use a specific transport:
uv run python samples/text_client_cli.py --transport GRPC

Type /quit or /exit to stop, or press Ctrl+C.

Quick Start

In two separate terminals:

# Terminal 1 — start the agent
uv run python samples/hello_world_agent.py

# Terminal 2 — start the client
uv run python samples/cli.py

Then type a message like hello and press Enter.