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 OutlineDriven/outline-driven-development --skill fastify-schema-first-servicegit clone --depth 1 https://github.com/OutlineDriven/outline-driven-developmentWrote 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/outlinedriven/outline-driven-development/fastify-schema-first-service)<a href="https://agentmods.dev/skills/outlinedriven/outline-driven-development/fastify-schema-first-service"><img src="https://agentmods.dev/badge/skills/outlinedriven/outline-driven-development/fastify-schema-first-service/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/outlinedriven/outline-driven-development/fastify-schema-first-service"><img src="https://agentmods.dev/badge/skills/outlinedriven/outline-driven-development/fastify-schema-first-service.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00064 | $0.01890 |
| Opus 5 | $0.00032 | $0.00945 |
| Sonnet 5 | $0.00013 | $0.00378 |
| Haiku 4.5 | $0.00006 | $0.00189 |
Grade A, and why
fastify-schema-first-service 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 6d 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 — 59 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Fastify schema first service
Contract
| Field | Bound contract |
|---|---|
| Trigger | Building or extending a Fastify application: routes, plugins, JSON Schema validation/serialization, hooks/lifecycle, decorators, content types, database wiring. |
| Authority | Reversible local writes to Fastify application code only; no deployment, credential, or remote mutation. |
| Side effect | Writes Fastify application code: route handlers, plugins, schemas, hooks, decorators, content-type parsers, and database wiring. |
| Done | Routes carry request+response schemas, validation errors are schema-shaped, decorators/hooks respect encapsulation, app boots with plugins in dependency order. |
Inputs
Required: the Fastify application entry point or the module to extend, and the target Node.js/Fastify version baseline.
Optional: existing route/plugin/schema files to modify, database adapter choice, TypeScript preference (type stripping vs compiled), and content-type requirements beyond JSON and text/plain.
Procedure
-
Bound scope. Identify the entry point (
app.ts/server.ts) and the files to add or change. Do not touch deployment config, credentials, or unrelated modules. Done when: the entry point and files to change are identified; deployment config, credentials, and unrelated modules are excluded. -
Define schemas first. For every route, define JSON Schema for the request parts that exist (
params,querystring,headers,body) and for the response (responsekeyed by status code). Prefer TypeBox (@sinclair/typebox) so TypeScript types derive from the same schema viaStatic<typeof Schema>. Register reusable schemas withapp.addSchema({ $id, ... })and reference them with$ref: '<id>#'. Done when: every route has JSON Schema for existing request parts and response, with reusable schemas registered viaaddSchema. -
Register routes with schemas. Use shorthand methods (
app.get,app.post) orapp.routewith the full options object. Attach the schema object to each route. Type route handlers with generics (app.post<{ Body, Params, Querystring, Reply }>). Organize routes by feature in separate files exporting a default plugin function. Done when: every route is registered with its schema object and typed handler.
What ships with it
1 file 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.
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.
- 6d ago First seen · 59 lines · 64 tokens per session scan A f50d054d7364
fastify-schema-first-service is a skill published in the GitHub repository OutlineDriven/outline-driven-development (52 stars, last pushed 4d ago), licensed Apache-2.0. It adds 64 tokens to every session and 1,890 once invoked, about $0.0003 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 2026-09-03.
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