agentmods.dev

update-a2a-proto

A maintenance workflow for updating an A2A Protocol Buffer file and regenerating its Java sources. A2A is a protocol for communication between AI agents, while Protocol Buffers define structured messages and services.

In plain words
What is it for?
Use it when the A2A specification changes, when syncing from the upstream repository, or when a new protocol version needs to be reflected in the Java SDK.
Why use it?
It provides a repeatable way to sync protocol changes while preserving the previous version and showing what changed.

Skill for Claude CodeCodex

481 4d ago A scan 60 tokens original Apache-2.0
View the source file a2aproject/a2a-java
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 skills/a2aproject/a2a-java/update-a2a-proto
Any agent
npx skills add a2aproject/a2a-java --skill update-a2a-proto
Clone the repo
git clone --depth 1 https://github.com/a2aproject/a2a-java

Made for: Claude Code, Codex.

Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 737 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00060 $0.00737
Opus 5 $0.00030 $0.00368
Sonnet 5 $0.00012 $0.00147
Haiku 4.5 $0.00006 $0.00074

Measured 2d ago against content hash 5fa2b7f041e4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

update-a2a-proto scanned grade A with 1 finding 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 2d ago.

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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

compatibility: Requires curl
.agents/skills/update-a2a-proto/SKILL.md · 86 lines

How it starts

The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Update a2a.proto

Update the A2A gRPC proto file from the upstream specification repository and regenerate Java sources.

Step 1: Capture the current state

Before updating, record what we have now so we can diff later.

  1. Read spec-grpc/src/main/proto/a2a.proto to note the current commit hash (located at the top of the file in a comment)
  2. Save a copy of the file for diffing:

Step 2: Download the updated specification

  1. Ask the user if they want to update from the main branch or pass a tag or a commit cheksum
  2. Download the latest a2a.proto from the upstream A2A repository at https://github.com/a2aproject/A2A/blob/main/specification/a2a.proto and save it to spec-grpc/src/main/proto/a2a.proto.
  3. Update the java_package option in the downloaded proto file to: 
    option java_package = "org.a2aproject.sdk.grpc";
  4. Update the comment tracking the upstream commit hash (line starting with // From commit) to the commit hash / tag of the downloaded proto file.

Step 3: Analyze specification changes

Compare the old and new versions of the specification to identify changes:

  1. Diff specification/a2a.proto with the backup to find:
    • New or changed message types
    • New or changed RPC methods
    • New or changed fields

Step 4: Regenerate gRPC classes

  1. Delete all the generated gRPC Java classes (in case of resources removed from the Protobuf definitions):

    find spec-grpc/src/main/java/org/a2aproject/sdk/grpc -maxdepth 1 -name "*.java" -delete```

  2. Regenerate gRPC Java classes by running:

    mvn generate-sources -pl spec-grpc -Dskip.protobuf.generate=false

Step 5: Update the code

Based on the spec diff, update the relevant files

Summarize the changes for the user before proceeding.

Step 6: Validate

Run the tests on all modules to verify the update

mvn clean install

Fix any issues before proceeding.

Step 7: Audit changes

Before committing, audit all code changes.

Read the full file on GitHub · 86 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. 2d ago First seen · 86 lines · 60 tokens per session scan A 5fa2b7f041e4

Subscribe to this mod's changes

update-a2a-proto is a skill published in the GitHub repository a2aproject/a2a-java (481 stars, last pushed 4d ago), licensed Apache-2.0. It adds 60 tokens to every session and 737 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Building agentsa2aa2a-clienta2a-serveragent2agentaihacktoberfest
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