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.
git clone --depth 1 https://github.com/hookdeck/agent-skillsWrote 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/rules/hookdeck/agent-skills/webhook-best-practices)<a href="https://agentmods.dev/rules/hookdeck/agent-skills/webhook-best-practices"><img src="https://agentmods.dev/badge/rules/hookdeck/agent-skills/webhook-best-practices/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/rules/hookdeck/agent-skills/webhook-best-practices"><img src="https://agentmods.dev/badge/rules/hookdeck/agent-skills/webhook-best-practices.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00020 | $0.00313 |
| Opus 5.5 | $0.00008 | $0.00125 |
| Sonnet 5.5 | $0.00004 | $0.00063 |
| Haiku 4.5 | $0.00002 | $0.00031 |
Grade A, and why
webhook-best-practices 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 1mo 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.
What it actually says
Webhook Best Practices
When building webhook handlers:
-
Always enable authentication at the source. Configure source authentication so Hookdeck verifies incoming requests (HMAC, Basic Auth, or API Key). Hookdeck rejects unverified requests and labels them "Verification Failed."
-
Always verify the Hookdeck signature. Hookdeck adds
x-hookdeck-signatureto requests forwarded to your handler. Verify this header before processing. When source verification is enabled, Hookdeck also setsx-hookdeck-verifiedtotrueon requests that passed source verification—you do not need to verify the provider's signature separately; verifying the Hookdeck signature is sufficient. See Hookdeck webhook signature verification. -
Handlers must be idempotent. Webhooks can be retried and may arrive multiple times. Design handlers to safely handle duplicates (e.g., check for existing records before creating, use idempotency keys).
Docs: authentication, sources. For verification code and setup, use the event-gateway skill.
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.
- 1mo ago First seen · 16 lines · 20 tokens per session scan A 92e2db7bbea7
webhook-best-practices is a cursor rule published in the GitHub repository hookdeck/agent-skills (5 stars, last pushed 16d ago), licensed MIT. It adds 20 tokens to every session and 313 once invoked, about $0.0001 per session on Opus 5.5. 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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