fasta2a

library0.6.1pypypi✓ verified 27d ago

Fasta2a (current version 0.6.0) is a Python library that converts an AI Agent into an A2A (Agent-to-Agent) server. It facilitates communication between AI agents by implementing the A2A protocol, allowing agents to expose their capabilities and interact programmatically. The library is relatively new but actively developed, with releases occurring every few months as the protocol specification evolves.

llm-agents web-framework http-networking

pip install fasta2a

github ↗package ↗homepage ↗docs ↗changelog ↗

INSTALL

IMPORT

SIG · FASTA2A

fasta2a

llm-agentspythonv0.6.1

Install

3.9s avg

Import

852ms

Disk

29MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.6.1 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.882s · 31.2MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 3.9s · import 0.822s · 31MB

29MB installed

● package 29MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

Broker

✓ from fasta2a import Broker

✗ from fasta2a.app import Fasta2aApp

FastA2A

✓ from fasta2a import FastA2A

Worker

✓ from fasta2a import Worker

This quickstart demonstrates how to create a basic Fasta2a application by initializing `Fasta2aApp` and defining an asynchronous message handler using the `@app.handle_message()` decorator. The handler processes `AgentMessage` objects and returns `AgentResponse` objects, optionally including `ToolCall`s. The example also shows how to run the application using `uvicorn`.

import uvicorn from fasta2a.app import Fasta2aApp from fasta2a.schema import AgentMessage, AgentResponse, ToolCall app = Fasta2aApp() @app.handle_message() async def my_agent_handler(message: AgentMessage) -> AgentResponse: """Handles incoming AgentMessage and returns an AgentResponse.""" print(f"Received message: {message.body}") if message.body == "hello": return AgentResponse(body="world") elif message.body == "call_tool": return AgentResponse( body="I am calling a hypothetical tool!", toolCalls=[ ToolCall( name="my_example_tool", arguments={"param1": "value1", "param2": 123} ) ] ) return AgentResponse(body=f"Unknown message: {message.body}") # To run this application, save it as, e.g., `main.py` # and execute from your terminal: # uvicorn main:app --host 0.0.0.0 --port 8000 # Then you can interact with it using an A2A client.

Debug

Known issues

breakingThe A2A protocol version support changes between `fasta2a` releases. For example, `v0.6.0` introduced support for `protocolVersion 0.3.0`. Older versions of `fasta2a` may not be compatible with newer protocol versions, and vice-versa, leading to parsing errors or unexpected agent behavior.

fix

Always check the release notes for the supported A2A protocol version for your `fasta2a` library version. Upgrade `fasta2a` to match the desired protocol version, or ensure your client/agent adheres to the protocol version supported by your `fasta2a` server.

affects: <0.6.0

gotchaThe core A2A schemas (`AgentMessage`, `AgentResponse`, `ToolCall`, `StreamMessageResponse`, etc.) are actively evolving as the protocol matures. Code relying on specific schema fields or structures might require updates with new `fasta2a` releases.

fix

Regularly review the `fasta2a` changelog and schema definitions when upgrading. Be prepared to adapt your agent logic and data models to new schema versions to maintain compatibility.

affects: All versions

gotchaFasta2a applications are ASGI applications and must be run with a compatible ASGI server (e.g., `uvicorn`) to be accessible. Simply running the Python script will define the application object but will not serve it over HTTP.

fix

To run your `fasta2a` application, use the command `uvicorn your_module_name:app --host 0.0.0.0 --port 8000` (replacing `your_module_name` with your script's filename). Do not attempt to run it directly as `python your_module_name.py`.

affects: All versions

Upgrade

Version history

0.6.1latest on PyPI · released May 15, 2026

Audit

Dependencies

fastapirequiredCore web framework for the ASGI application.

uvicornrequiredASGI server for running the application.

pydanticrequiredData validation and settings management.

pydantic-settingsrequiredSettings management for FastAPI applications.

anyiorequiredAsynchronous I/O primitives.

Agent activity