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 quo-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/quo-webhooks)<a href="https://agentmods.dev/skills/hookdeck/webhook-skills/quo-webhooks"><img src="https://agentmods.dev/badge/skills/hookdeck/webhook-skills/quo-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/quo-webhooks"><img src="https://agentmods.dev/badge/skills/hookdeck/webhook-skills/quo-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 | $0.00167 | $0.05359 |
| Opus 5.5 | $0.00067 | $0.02144 |
| Sonnet 5.5 | $0.00033 | $0.01072 |
| Haiku 4.5 | $0.00017 | $0.00536 |
Grade A, and why
quo-webhooks 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 23d 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.
curl -X POST https://api.quo.com/webhooks \ How it starts
The opening of the file, as written. The whole thing — 378 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Quo Webhooks
Quo (quo.com) is a business phone / VoIP platform. It sends webhooks for calls, messages, contacts and tasks.
Quo is the platform formerly known as OpenPhone. The support docs say so verbatim: "Send real-time notifications of Quo, formerly OpenPhone, events to your applications". The rebrand is why the legacy signature header is still called
openphone-signature, and why older community material talks about OpenPhone webhooks. API host ishttps://api.quo.com; docs live atwww.quo.com/docsandsupport.quo.com.
Not Quoter. Quoter (help.quoter.com) is an unrelated CPQ / sales-quoting company with an MD5-based
hashform field (not a header). Quo uses HMAC-SHA256. Two different companies, two entirely different signing schemes. Also not Quora, not the Quo card/loyalty app, and not Twilio.
When to Use This Skill
- How do I receive Quo (OpenPhone) webhooks?
- How do I verify a Quo webhook signature?
- Why is my
webhook-signature/openphone-signatureverification failing? - How do I handle
message.received,call.completed, orcall.summary.completedevents? - What is the difference between
data.resourceanddata.objectin a Quo payload? - How do I deduplicate Quo webhook deliveries?
- Does Quo send a validation / challenge request when I add an endpoint?
Two Generations, Two Signature Schemes
This is the first thing to get right. Which scheme an endpoint receives is decided by how the webhook subscription was created, not by anything you configure on your server. A handler that may receive both must implement both.
| Scheme A — current | Scheme B — legacy | |
|---|---|---|
| Created via | POST /webhooks with Quo-Api-Version: 2026-03-30 |
legacy /v1/webhooks/messages, /v1/webhooks/calls, … |
| Header(s) | webhook-id, webhook-timestamp, webhook-signature |
openphone-signature (single header) |
| Header format | webhook-signature: v1,<base64> v1,<base64> (space-separated) |
hmac;1;1639710054089;mw1K4fv…= (semicolon-separated, 4 fields) |
| Signed content | {webhook-id}.{webhook-timestamp}.{raw-body} |
{timestamp}.{raw-body} |
| Timestamp unit | UNIX seconds | UNIX milliseconds (inferred — see below) |
| Secret | key from POST /webhooks, whsec_<base64> |
app → webhook → ⋯ → "Reveal signing secret", bare base64 |
| Envelope | data.resource / data.context / data.links |
data.object |
apiVersion |
"2026-03-30" |
"v2" ("v3" for AI events) |
What ships with it
20 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 2.2 KB
- examples/express/package.json 523 B
- examples/express/README.md 7.9 KB
- examples/express/src/index.js 17 KB runs code
- examples/express/test/webhook.test.js 15 KB runs code
- examples/fastapi/.env.example 2.2 KB
- examples/fastapi/main.py 16 KB runs code
- examples/fastapi/README.md 9.8 KB
- examples/fastapi/requirements.txt 82 B
- examples/fastapi/test_webhook.py 17 KB runs code
- examples/nextjs/.env.example 2.3 KB
- examples/nextjs/app/webhooks/quo/route.ts 16 KB runs code
- examples/nextjs/package.json 601 B
- examples/nextjs/README.md 7.0 KB
- examples/nextjs/test/webhook.test.ts 14 KB runs code
- examples/nextjs/vitest.config.ts 162 B runs code
- references/overview.md 11 KB
- references/setup.md 8.9 KB
- references/verification.md 19 KB
- TODO.md 1.3 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.
- 23d ago First seen · 378 lines · 167 tokens per session scan A f9ee08e874ff
quo-webhooks is a skill published in the GitHub repository hookdeck/webhook-skills (92 stars, last pushed today), licensed MIT. It adds 167 tokens to every session and 5,359 once invoked, about $0.0007 per session on Opus 5.5. 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 2026-09-24.
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