a2a-java AGENTS.md

Project instructions for a2a-java, a multi-module Java SDK for the Agent2Agent Protocol, which lets AI agents communicate through JSON-RPC, gRPC, and REST.

In plain words
What is it for?
Use them to build and navigate client, server, transport, protocol, reference-server, and compatibility modules.
Why use it?
They explain the modules, Java requirement, build command, and protocol-related structure so changes land in the right part of the SDK.

Instructions file for CodexOpenCode

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add instructions/a2aproject/a2a-java/agents-md
Clone the repo
git clone --depth 1 https://github.com/a2aproject/a2a-java

Made for: Codex, OpenCode.

Per session 1,815 This file is loaded in full into every session.
When invoked 1,815 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.01815 $0.01815
Opus 5 $0.00907 $0.00907
Sonnet 5 $0.00363 $0.00363
Haiku 4.5 $0.00181 $0.00181

Measured yesterday against content hash b15c2fbfa073, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

a2a-java AGENTS.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

AGENTS.md · 132 lines

How it starts

The opening of the file, as written. The whole thing — 132 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md

Project Overview

Java SDK for the Agent2Agent (A2A) Protocol. Multi-module Maven project (org.a2aproject.sdk group) providing client and server libraries for A2A agent communication over JSON-RPC, gRPC, and REST transports.

Build

Requires Java 17+. Tests output is redirected to files by default.

mvn clean install

Project Structure

  • spec/ — A2A specification types (Java records for the protocol)
  • spec-grpc/ — gRPC protobuf definitions and generated classes
  • common/ — Shared utilities used across modules
  • client/ — Client SDK
    • base/ — Core client API
    • transport/spi/ — Transport SPI
    • transport/jsonrpc/, transport/grpc/, transport/rest/ — Transport implementations
  • server-common/ — Server-side core (AgentExecutor, TaskStore, QueueManager)
  • transport/ — Server transport layer (jsonrpc, grpc, rest)
  • http-client/ — HTTP client abstraction
  • jsonrpc-common/ — Shared JSON-RPC utilities
  • reference/ — Reference server implementations built on Quarkus
    • common/, jsonrpc/, grpc/, rest/
    • multiversion-jsonrpc/, multiversion-rest/ — Multi-version dispatching (v1.0 + v0.3)
  • tck/ — Technology Compatibility Kit (protocol conformance tests)
  • tests/ — Integration and server-common tests
    • server-common/ — Server-common integration tests
    • multiversion/ — Multi-version integration tests (jsonrpc, rest, grpc)
  • extras/ — Optional add-ons
    • common/ — Shared classes across extras modules
    • opentelemetry/ — OpenTelemetry integration
    • task-store-database-jpa/ — JPA-backed task store
    • push-notification-config-store-database-jpa/ — JPA-backed push notification config store
    • queue-manager-replicated/ — Kafka-based replicated queue manager
    • http-client-vertx/ — Vert.x HTTP client
    • http-client-android/ — Android HTTP client
  • compat-0.3/ — Backward compatibility layer for A2A protocol v0.3
  • integrations/ — Runtime integrations (e.g., MicroProfile Config)
  • test-utils-docker/ — Test utilities for conditional Docker-based test execution
  • boms/ — Bill of Materials POMs (sdk, extras, reference, test-utils)
  • examples/ — Sample applications (helloworld, cloud-deployment)

Read the full file on GitHub · 132 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 132 lines · 1,815 tokens per session scan A b15c2fbfa073

Subscribe to this mod's changes

a2a-java AGENTS.md is an instructions file published in the GitHub repository a2aproject/a2a-java (481 stars, last pushed 4d ago), licensed Apache-2.0. It adds 1,815 tokens to every session, about $0.0091 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.