a2a-go

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 Go to latest Published: Feb 23, 2026 License: Apache-2.0

README

A2A Go SDK

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A2A Logo

A Go library for running agentic applications as A2A Servers, following the Agent2Agent (A2A) Protocol.

✨ Features

  • A2A Protocol Compliant: Build agentic applications that adhere to the Agent2Agent (A2A) Protocol.
  • Extensible: Easily add support for different communication protocols and database backends.

🚀 Getting Started

Requires Go 1.24.4 or newer:

go get github.com/a2aproject/a2a-go

Visit pkg.go for a full documentation.

Examples

For a simple example refer to the helloworld example.

Server

For a full documentation visit pkg.go.dev/a2asrv.

  1. Create a transport-agnostic A2A request handler:

    var options []a2asrv.RequestHandlerOption = newCustomOptions()
var agentExecutor a2asrv.AgentExecutor = newCustomAgentExecutor()
requestHandler := a2asrv.NewHandler(agentExecutor, options...)

  2. Wrap the handler into a transport implementation:

    grpcHandler := a2agrpc.NewHandler(requestHandler)

// or

jsonrpcHandler := a2asrv.NewJSONRPCHandler(requestHandler)

  3. Register handler with a server, for example:

    import "google.golang.org/grpc"
...
server := grpc.NewServer()
grpcHandler.RegisterWith(server)
err := server.Serve(listener)
Client

For a full documentation visit pkg.go.dev/a2aclient.

  1. Resolve an AgentCard to get an information about how an agent is exposed.

    card, err := agentcard.DefaultResolver.Resolve(ctx)

  2. Create a transport-agnostic client from the AgentCard:

    var options a2aclient.FactoryOption = newCustomClientOptions()
client, err := a2aclient.NewFromCard(ctx, card, options...)

  3. The connection is now open and can be used to send requests to a server:

    msg := a2a.NewMessage(a2a.MessageRoleUser, a2a.TextPart{Text: "..."})
resp, err := client.SendMessage(ctx, &a2a.MessageSendParams{Message: msg})

🌐 More Examples

You can find a variety of more detailed examples in the a2a-samples repository.

🤝 Contributing

Contributions are welcome! Please see the CONTRIBUTING.md file for guidelines on how to get involved.

Before starting work on a new feature or significant change, please open an issue to discuss your proposed approach with the maintainers. This helps ensure your contribution aligns with the project's goals and prevents duplicated effort or wasted work.

📄 License

This project is licensed under the Apache 2.0 License. See the LICENSE file for more details.

Directories

Path Synopsis
Package a2a contains core types and constants from the A2A protocol shared by client and server implementations.
 Package a2a contains core types and constants from the A2A protocol shared by client and server implementations.
Package a2aclient provides a transport-agnostic A2A client implementation.
 Package a2aclient provides a transport-agnostic A2A client implementation.
agentcard
Package agentcard provides utilities for fetching public a2a.AgentCard.
 Package agentcard provides utilities for fetching public a2a.AgentCard.
a2acompat
a2av0
Package a2av0 contains 0.3-compatible agent card type definition.
 Package a2av0 contains 0.3-compatible agent card type definition.
Package a2aext provides utilities for A2A extension implementers.
 Package a2aext provides utilities for A2A extension implementers.
a2agrpc
v0
Package a2agrpc provides an A2A gRPC service implementation which can be registered with grpc.Server.
 Package a2agrpc provides an A2A gRPC service implementation which can be registered with grpc.Server.
v1
Package a2agrpc provides an A2A gRPC service implementation which can be registered with grpc.Server.
 Package a2agrpc provides an A2A gRPC service implementation which can be registered with grpc.Server.
a2apb
v0
Package a2apb contains types and interfaces generated from published official A2A .proto 0.3 specification.
 Package a2apb contains types and interfaces generated from published official A2A .proto 0.3 specification.
v0/pbconv
Package pbconv provides conversion functions between A2A protobufs and native Go types.
 Package pbconv provides conversion functions between A2A protobufs and native Go types.
v1
Package a2apb contains types and interfaces generated from published official A2A .proto v1.0 specification.
 Package a2apb contains types and interfaces generated from published official A2A .proto v1.0 specification.
v1/pbconv
Package pbconv provides conversion functions between A2A protobufs and native Go types.
 Package pbconv provides conversion functions between A2A protobufs and native Go types.
Package a2asrv provides a configurable A2A protocol server implementation.
 Package a2asrv provides a configurable A2A protocol server implementation.
eventqueue
Package eventqueue provides implementation for in-memory queue management and event processing.
 Package eventqueue provides implementation for in-memory queue management and event processing.
limiter
Package limiter provides configurations for controlling concurrency limit.
 Package limiter provides configurations for controlling concurrency limit.
push
Package push provides a basic implementation of push notification functionality.
 Package push provides a basic implementation of push notification functionality.
taskstore
Package taskstore provides the contract and in-memory implementation of a2a.Task storage.
 Package taskstore provides the contract and in-memory implementation of a2a.Task storage.
workqueue
Package workqueue provides a work queue implementation for task execution.
 Package workqueue provides a work queue implementation for task execution.
e2e
tck command
Package main provides a TCK core agent implementation for testing.
 Package main provides a TCK core agent implementation for testing.
examples
clustermode/client command
Package main provides a cluster mode client example.
 Package main provides a cluster mode client example.
clustermode/server command
Package main provides a cluster mode server example.
 Package main provides a cluster mode server example.
helloworld/client command
Package main provides a hello world client example.
 Package main provides a hello world client example.
helloworld/server/grpc command
Package main provides a hello world gRPC server example.
 Package main provides a hello world gRPC server example.
helloworld/server/jsonrpc command
Package main provides a hello world JSON-RPC server example.
 Package main provides a hello world JSON-RPC server example.
helloworld/server/rest command
Package main provides a hello world REST server example.
 Package main provides a hello world REST server example.
internal
eventpipe
Package eventpipe provides a simple eventqueue.Queue implementation which is used to connect [a2asrv.AgentExecutor] with event processor.
 Package eventpipe provides a simple eventqueue.Queue implementation which is used to connect [a2asrv.AgentExecutor] with event processor.
grpcutil
Package grpcutil provides gRPC utility functions for A2A.
 Package grpcutil provides gRPC utility functions for A2A.
jsonrpc
Package jsonrpc provides JSON-RPC 2.0 protocol implementation for A2A.
 Package jsonrpc provides JSON-RPC 2.0 protocol implementation for A2A.
rest
Package rest provides REST protocol constants and error handling for A2A.
 Package rest provides REST protocol constants and error handling for A2A.
sse
Package sse provides Server-Sent Events (SSE) implementation for A2A.
 Package sse provides Server-Sent Events (SSE) implementation for A2A.
taskexec
Package taskexec provides a concurrent agent invocation manager.
 Package taskexec provides a concurrent agent invocation manager.
taskupdate
Package taskupdate provides types and utilities for performing a2a.Task updates in response to a2a.Event-s.
 Package taskupdate provides types and utilities for performing a2a.Task updates in response to a2a.Event-s.
testutil
Package testutil provides utilities for easier test setup
 Package testutil provides utilities for easier test setup
testutil/testexecutor
Package testexecutor provides mock implementations for agent executor for testing.
 Package testexecutor provides mock implementations for agent executor for testing.
utils
Package utils provides general utility functions for A2A.
 Package utils provides general utility functions for A2A.
Package log provides utilities for attaching an slog.Logger configured with request-specific attributes to context.Context.
 Package log provides utilities for attaching an slog.Logger configured with request-specific attributes to context.Context.

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