Go (single-skill demo)

This page is generated from the A2A Pack language SDK metadata.

Read this first

Go and Rust support exactly one skill.

The Go and Rust SDKs implement the demo contract only: a single skill named sum that adds two numbers. The worker serves just POST /_a2a/invoke/sum, and the .a2a/agent.dsl.json they compile always declares that one skill.

A second skill is never routed and never advertised on the agent card. In Go the extra method compiles and deploys with no error anywhere, and is then simply unreachable. In Rust a second method inside the impl A2AAgent block does not compile at all (E0407); moved to a separate inherent impl block it compiles and is then unreachable just like Go's. Treat these two SDKs as a proof-of-concept for the sidecar worker protocol.

For an agent with more than one tool, use a2a init --language python or a2a init --language typescript.

Scaffold

a2a init math-agent --language go

Implementation Contract

Implement the a2apack.Agent interface and call a2apack.CompileAgent / a2apack.ServeAgent.

type MathAgent struct{}

func (MathAgent) Definition() a2apack.AgentDefinition {
    return a2apack.AgentDefinition{Name: "math-agent", Description: "Math helper", Version: "0.1.0"}
}

func (MathAgent) Sum(ctx context.Context, request a2apack.SumRequest) (a2apack.SumResponse, error) {
    return a2apack.SumResponse{Value: request.Left + request.Right}, nil
}

Local Commands

go run . compile
go run . worker

SDK Package

a2acloud.io/a2a-pack-go vendored at third_party/a2a-pack-go.

The compiled .a2a/agent.dsl.json is the sidecar contract. The sidecar owns public A2A, MCP, frontend, and invoke endpoints; the language SDK owns native handler execution through the worker protocol.