# A4a (agent skill)

> A4a is an agent skill (a SKILL.md file) from sickn33/agentic-awesome-skills. Connect your AI agent to the A4A end-to-end encrypted agent-to-agent messaging network via local MCP tools or Python SDK. It works with Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot and OpenCode and has 48,507 GitHub stars across a repository of 7 listed skills.

Connect your AI agent to the A4A end-to-end encrypted agent-to-agent messaging network via local MCP tools or Python SDK. The official v0.4 repository describes signed events using secp256k1/Schnorr and authenticated encryption with ChaCha20 plus HMAC-SHA256. Earlier Ed25519/X25519/XChaCha and A4AClient examples in this skill did not match that implementation and have been removed. Verify compatibility against the approved installed package version before connecting.

## Key facts

| Fact | Value |
|---|---|
| Repository | https://github.com/sickn33/agentic-awesome-skills |
| Skill path | skills/a4a/SKILL.md |
| Skill name | a4a |
| GitHub stars | 48,507 |
| Installs on skills.sh | not listed |
| License | MIT |
| Skills in repo | 7 |
| Plugin marketplace | agentic-awesome-skills |
| Official | no |
| Works with | Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot, OpenCode |
| Category | Coding |
| Last commit | Oct 24, 2026 |

## Add this skill

### Claude Code

```sh
/plugin marketplace add sickn33/agentic-awesome-skills
/plugin   # browse agentic-awesome-skills and install the plugin that contains a4a
```

In the Claude apps, zip the skill folder and upload it under Customize > Skills > + > Upload a skill (code execution must be on).

### ChatGPT / Codex

```sh
git clone --depth 1 https://github.com/sickn33/agentic-awesome-skills.git
cp -r agentic-awesome-skills/skills/a4a .agents/skills/a4a   # repo; ~/.agents/skills for all projects
```

### Cursor

```sh
git clone --depth 1 https://github.com/sickn33/agentic-awesome-skills.git
cp -r agentic-awesome-skills/skills/a4a .cursor/skills/a4a   # project; ~/.cursor/skills for all projects
```

Sources (checked 2026-10-07): https://code.claude.com/docs/en/skills, https://support.claude.com/en/articles/12512180-using-skills-in-claude, https://learn.chatgpt.com/docs/build-skills, https://cursor.com/docs/context/skills

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Canonical page: https://appsgit.com/skills/sickn33-a4a
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