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.
npx skills add aksika/abtars --skill a2a-communicationgit clone --depth 1 https://github.com/aksika/abtarsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/aksika/abtars/a2a-communication)<a href="https://agentmods.dev/skills/aksika/abtars/a2a-communication"><img src="https://agentmods.dev/badge/skills/aksika/abtars/a2a-communication.svg" alt="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00020 | $0.00651 |
| Opus 5 | $0.00010 | $0.00326 |
| Sonnet 5 | $0.00004 | $0.00130 |
| Haiku 4.5 | $0.00002 | $0.00065 |
Grade A, and why
a2a-communication 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 8d 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.
- **NEVER** call a peer endpoint manually (curl/http) without JWT — you'll get 401 How it starts
The opening of the file, as written. The whole thing — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Peer Communication (peer_ask)
Talk to other abtars instances configured in ~/.abtars/config/peers.json.
When to use
- You need information or action from another agent
- The user explicitly asks you to delegate to a peer ("ask ...", "tell to...")
- A task requires capabilities only available on the other host
When NOT to use
- The user is talking to you directly — don't forward their message to a peer unless asked
- Simple questions you can answer yourself
- Anything time-critical under 1 second (peer_ask blocks for up to 60s)
Usage
peer_ask(peer_name="<peer>", prompt="What's the current disk usage?")
peer_ask(peer_name="<peer>", prompt="Run 'abtars status' and report back")
Available peers
Check ~/.abtars/config/peers.json for configured peer names. If no peers configured, the tool returns an error listing "(none)".
Behavior
- Blocks until the peer responds (up to 60s timeout)
- Hop limit prevents infinite loops (max 12 hops across the chain)
- Each call is logged as PEER_CALL in the bridge log
- The peer processes your prompt as if a user sent it — full agent capabilities on their side
If peer_ask fails (connection refused / timeout)
The peer may be behind a firewall that blocks inbound TCP. Use the doorbell:
peer_doorbell(peer_name="<peer>")
This sends a signed UDP doorbell on port 5353 that tells the peer to establish a direct WSS connection. Flow:
peer_ask("<peer>", "your question")→ fails (ECONNREFUSED)peer_doorbell("<peer>")→ sends signed doorbell query- Peer receives doorbell → initiates outbound WSS connect to you
- WSS route established — retry
peer_ask
Always try peer_ask first. Only use peer_doorbell if direct call fails. The doorbell requests a WSS refresh, not a direct answer.
Authentication (CRITICAL)
- All peer calls use JWT-HS256 auth automatically (
peer-jwt.ts) - The shared secret is the
tokenfield inpeers.jsonfor each peer - JWT is sent as
Authorization: Bearer <token>header - NEVER call a peer endpoint manually (curl/http) without JWT — you'll get 401
- Always use
peer_ask()tool which handles signing automatically - If you get 401 from a peer, it means auth failed — check token match, clock skew, or peer name mismatch (iss/aud)
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.
- 8d ago First seen · 69 lines · 20 tokens per session scan A fd97d77aaaef
a2a-communication is a skill published in the GitHub repository aksika/abtars (9 stars, last pushed today), licensed Apache-2.0. It adds 20 tokens to every session and 651 once invoked, about $0.0001 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 2026-08-31.
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