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 sparkpost-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/sparkpost-webhooks)<a href="https://agentmods.dev/skills/hookdeck/webhook-skills/sparkpost-webhooks"><img src="https://agentmods.dev/badge/skills/hookdeck/webhook-skills/sparkpost-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/sparkpost-webhooks"><img src="https://agentmods.dev/badge/skills/hookdeck/webhook-skills/sparkpost-webhooks.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 | $0.00108 | $0.03261 |
| Opus 5.5 | $0.00043 | $0.01304 |
| Sonnet 5.5 | $0.00022 | $0.00652 |
| Haiku 4.5 | $0.00011 | $0.00326 |
Grade A, and why
sparkpost-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 18d 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 — 234 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SparkPost Webhooks
When to Use This Skill
- How do I receive SparkPost webhooks?
- How do I authenticate SparkPost webhooks? (there is no signature to verify)
- Why is my SparkPost webhook returning 401 / why won't SparkPost create my webhook?
- How do I parse the SparkPost
msysbatch payload? - How do I handle
delivery,bounce,click,open,spam_complaintevents? - What is
X-MessageSystems-Batch-IDand how do I deduplicate batches? - How do I handle SparkPost relay webhooks (inbound email)?
Critical: SparkPost Event Webhooks Are Not Signed
There is no HMAC, no signature header, and no signing secret. Do not look for one —
any code that computes createHmac / hmac.new for a SparkPost event webhook is wrong.
Authentication is credential-based and optional, set by the webhook's auth_type
field, whose values are exactly none | basic | oauth2. From SparkPost's
"Event Webhook Authentication and Security" doc: "The authentication method is set to
'None' by default when creating a new webhook."
| Mode | auth_type |
What SparkPost sends |
|---|---|---|
| Basic Auth (recommended) | basic |
Authorization: Basic base64(username:password) |
| OAuth 2.0 client credentials | oauth2 |
Authorization: Bearer {token} |
| Legacy token (deprecated) | — (auth_token field) |
X-MessageSystems-Webhook-Token: <token> |
| None (default) | none |
nothing |
Your handler must fail closed: if no credentials are configured, reject. Never accept unauthenticated batches silently.
Not to be confused with Bird's new platform webhooks (bird.com). SparkPost is now owned by Bird, and the old
www.sparkpost.com/docs/tech-resources/webhook-authentication/URL 301-redirects to Bird's docs — but that is a different product with its own Standard Webhooks signing (webhook-id/webhook-timestamp/webhook-signature,whsec_secrets,email.delivered-style event names). None of that applies here.
What ships with it
21 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 1.6 KB
- examples/express/package.json 449 B
- examples/express/README.md 4.6 KB
- examples/express/src/index.js 20 KB runs code
- examples/express/test/webhook.test.js 18 KB runs code
- examples/fastapi/.env.example 1.5 KB
- examples/fastapi/main.py 22 KB runs code
- examples/fastapi/README.md 5.6 KB
- examples/fastapi/requirements.txt 82 B
- examples/fastapi/test_webhook.py 19 KB runs code
- examples/nextjs/.env.example 1.5 KB
- examples/nextjs/app/oauth/token/route.ts 3.2 KB runs code
- examples/nextjs/app/webhooks/sparkpost/route.ts 13 KB runs code
- examples/nextjs/lib/sparkpost-auth.ts 7.5 KB runs code
- examples/nextjs/package.json 527 B
- examples/nextjs/README.md 5.0 KB
- examples/nextjs/test/webhook.test.ts 19 KB runs code
- examples/nextjs/vitest.config.ts 162 B runs code
- references/overview.md 13 KB
- references/setup.md 10 KB
- references/verification.md 14 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.
- 18d ago First seen · 234 lines · 108 tokens per session scan A fc0ab1114c07
sparkpost-webhooks is a skill published in the GitHub repository hookdeck/webhook-skills (92 stars, last pushed yesterday), licensed MIT. It adds 108 tokens to every session and 3,261 once invoked, about $0.0004 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 2026-09-29.
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