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 hookdeck/webhook-skills --skill alchemy-webhooksgit clone --depth 1 https://github.com/hookdeck/webhook-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/skills/hookdeck/webhook-skills/alchemy-webhooks)<a href="https://agentmods.dev/skills/hookdeck/webhook-skills/alchemy-webhooks"><img src="https://agentmods.dev/badge/skills/hookdeck/webhook-skills/alchemy-webhooks/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/skills/hookdeck/webhook-skills/alchemy-webhooks"><img src="https://agentmods.dev/badge/skills/hookdeck/webhook-skills/alchemy-webhooks.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium MCP Rug Pull · line 101 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
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 | $0.00051 | $0.01651 |
| Opus 5.5 | $0.00020 | $0.00660 |
| Sonnet 5.5 | $0.00010 | $0.00330 |
| Haiku 4.5 | $0.00005 | $0.00165 |
Grade A, and why
alchemy-webhooks 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 2mo 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 — 138 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Alchemy Webhooks
When to Use This Skill
- How do I receive Alchemy webhooks?
- How do I verify Alchemy webhook signatures (the
X-Alchemy-Signatureheader)? - How do I handle ADDRESS_ACTIVITY, NFT_ACTIVITY, or GRAPHQL events?
- Why is my Alchemy webhook signature verification failing?
- How do I set up Alchemy Notify webhooks for onchain activity?
Verification (core)
Alchemy signs every webhook with HMAC-SHA256 over the raw request body, hex-encoded, in the
X-Alchemy-Signature header. There is no sha256= prefix and no timestamp — just the hex digest.
The key is the per-webhook signing key (copied from the top-right of that webhook's detail page in
the Notify dashboard, or fetched via the Notify API), not your app's Auth Token.
The alchemy-sdk npm package manages webhook CRUD but does not verify signatures — implement HMAC
yourself. Always compute the HMAC over the raw body; a re-serialized JSON body will not match.
const crypto = require('crypto');
function verifyAlchemySignature(rawBody, signature, signingKey) {
if (!signature) return false;
const digest = crypto
.createHmac('sha256', signingKey)
.update(rawBody, 'utf8') // rawBody: exact bytes/string received, never re-stringified JSON
.digest('hex');
try {
return crypto.timingSafeEqual(Buffer.from(signature), Buffer.from(digest));
} catch {
return false; // length mismatch = invalid
}
}
For complete handlers with route wiring, event dispatch, and tests, see:
Common Event Types
The webhook type field identifies the event. Alchemy webhooks are scoped per chain/network.
| Type | Triggered When |
|---|---|
ADDRESS_ACTIVITY |
ETH/ERC-20/ERC-721/ERC-1155 transfers involving tracked addresses |
NFT_ACTIVITY |
ERC-721/ERC-1155 transfers for tracked NFT contracts |
GRAPHQL |
A Custom Webhook GraphQL query matches new onchain data |
What ships with it
19 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- examples/express/.env.example 218 B
- examples/express/package.json 377 B
- examples/express/README.md 1.1 KB
- examples/express/src/index.js 4.7 KB runs code
- examples/express/test/webhook.test.js 4.8 KB runs code
- examples/fastapi/.env.example 149 B
- examples/fastapi/main.py 4.2 KB runs code
- examples/fastapi/README.md 1.4 KB
- examples/fastapi/requirements.txt 82 B
- examples/fastapi/test_webhook.py 5.7 KB runs code
- examples/nextjs/.env.example 149 B
- examples/nextjs/app/webhooks/alchemy/route.ts 3.8 KB runs code
- examples/nextjs/package.json 489 B
- examples/nextjs/README.md 1.1 KB
- examples/nextjs/test/webhook.test.ts 3.3 KB runs code
- examples/nextjs/vitest.config.ts 140 B runs code
- references/overview.md 4.9 KB
- references/setup.md 3.4 KB
- references/verification.md 4.8 KB
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.
- 2mo ago Changed · +16 lines · -13 tokens per session 30b8ca4774f9
- 2mo ago First seen · 122 lines · 64 tokens per session scan A c6dc52c29b54
alchemy-webhooks is a skill published in the GitHub repository hookdeck/webhook-skills (98 stars, last pushed yesterday), licensed MIT. It adds 51 tokens to every session and 1,651 once invoked, about $0.0002 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 2026-08-30.
alchemy-webhooks compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| alchemy-webhookshookdeck/webhook-skills | Skill | 98 | yesterday | MIT | A | 51 | Claude Code, Codex |
| imagegenopenai/codex | Skill | 133k | yesterday | Apache-2.0 | A | 113 | Codex |
| playwright-climicrosoft/playwright | Skill | 99k | yesterday | Apache-2.0 | A | 19 | Claude Code |
| local-ai-agentsmicrosoft/ai-agents-for-beginners | Skill | 79k | 4d ago | MIT | A | 200 | Claude Code, Codex |
| systematic-debuggingobra/superpowers | Skill | 313k | 3d ago | MIT | A | 21 | Claude Code |
| next-cache-components-adoptionvercel/next.js | Skill | 143k | today | MIT | A | 95 | Claude Code |
| next-partial-prefetching-adoptionvercel/next.js | Skill | 143k | today | MIT | A | 103 | Claude Code |