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 oaslananka/a2amesh --skill a2a-endpoint-validationgit clone --depth 1 https://github.com/oaslananka/a2ameshWrote 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/oaslananka/a2amesh/a2a-endpoint-validation)<a href="https://agentmods.dev/skills/oaslananka/a2amesh/a2a-endpoint-validation"><img src="https://agentmods.dev/badge/skills/oaslananka/a2amesh/a2a-endpoint-validation.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00031 | $0.00608 |
| Opus 5 | $0.00015 | $0.00304 |
| Sonnet 5 | $0.00006 | $0.00122 |
| Haiku 4.5 | $0.00003 | $0.00061 |
Grade A, and why
a2a-endpoint-validation 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 7d 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.
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.
How it starts
The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.
A2A Endpoint Validation
Use this skill to establish bounded evidence about an A2A endpoint before sending work to it.
When to use
Use this skill when the user asks to:
- inspect or validate an Agent Card;
- discover an A2A endpoint;
- check endpoint health or protocol conformance;
- establish whether an endpoint is suitable for a later task workflow; or
- compare declared capabilities with observed read-only behavior.
Do not treat a successful probe as proof that an endpoint is trustworthy, approved for production use, or authorized for sensitive data.
Required context
Collect or confirm:
- the exact endpoint URL or Agent Card path;
- whether the endpoint is local, public, or on a private network;
- the expected protocol version and authentication method;
- the expected tenant or trust boundary, when applicable; and
- the permitted validation depth: metadata only, health, or conformance.
Never request concrete secret values in chat. Refer to credential variable names or an already configured runtime secret source.
Workflow
- Start with local CLI diagnostics:
pnpm dlx @a2amesh/cli doctor --json. - Validate a file-backed Agent Card with
pnpm dlx @a2amesh/cli validate <path>or inspect an endpoint withdiscover. - Run
healthbefore a broader conformance check. - Use
conformanceonly against an endpoint the user is authorized to test. - Keep private-network access disabled unless the user explicitly authorizes the destination and
--allow-private-networkis necessary. - Record the endpoint, command category, observed protocol/capabilities, bounded failures, and remaining unknowns.
- Stop before any message send, task cancellation, registry import, or other state-changing action.
Safety boundaries
- This workflow is read-only.
- Do not bypass TLS, authentication, tenant, audience, or outbound-network policy.
- Do not infer trust from a reachable health route.
- Do not echo authorization headers, tokens, URL query credentials, or private Agent Card fields.
- Do not probe private or link-local destinations without explicit authorization.
- Treat redirects as new destinations that require the same outbound-policy checks.
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.
- 7d ago First seen · 76 lines · 31 tokens per session scan A 5b01c33ec1df
a2a-endpoint-validation is a skill published in the GitHub repository oaslananka/a2amesh (2 stars, last pushed 3d ago), licensed Apache-2.0. It adds 31 tokens to every session and 608 once invoked, about $0.0002 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 2026-08-31.
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