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Agent skill

Spine API

by jeremylongshore in jeremylongshore/tons-of-skills-marketplace

Design and spec an API — endpoints, request/response shapes, error codes, auth pattern, pagination.

MITAuto-check: notesBackend & APIs

Install Spine API

skills CLI
$ npx skills add jeremylongshore/tons-of-skills-marketplace --skill spine-api -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install jeremylongshore/tons-of-skills-marketplace spine-api --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/jeremylongshore/tons-of-skills-marketplace.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/ai-agency/tonone/skills/spine-api .claude/skills/spine-api && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
spine-api
GitHub stars
2.8k
Token cost
~2k tokens
SKILL.md length
768 words
Files
2
Skills in repo
3,342
Repo updated
First seen
Licence
MIT

At a glance

Design and spec an API — endpoints, request/response shapes, error codes, auth pattern, pagination.

  • Works in 8 steps: Detect Environment → Clarify (only if genuinely blocked) → Produce the API Spec → …
  • Asked to design an API
  • SKILL.md covers Steps and Delivery
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Spine API is an agent skill from jeremylongshore/tons-of-skills-marketplace. Design and spec an API — endpoints, request/response shapes, error codes, auth pattern, pagination. Applies Stripe's consistency principles. Use when asked to "design an API", "build API endpoints", "create REST API", or "API for this feature".

Its SKILL.md is about 2k tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files (for example `.claude-plugin/plugin.json`).

It sits in Backend & APIs, covering REST APIs and API design. It works with Stripe. The repository describes itself as: Model-agnostic agent-skills platform with a harness-free canonical layer, verified adapters, and the ccpi package manager. Explore at tonsofskills.com. The licence is MIT.

When your agent uses it

  • Asked to design an API
  • Build API endpoints
  • Create REST API
  • API for this feature

Example prompts

  • “s consistency principles. Use when asked to”
  • “build API endpoints”
  • “create REST API”
  • “/spine-api”

Requirements

  • Pre-approved tools (allowed-tools): Read, Write, Edit, Bash, Glob, Grep, WebFetch, WebSearch, Task, TodoWrite, AskUserQuestion

Workflow steps

8 steps, taken from the step headings in SKILL.md.

  1. Detect Environment
  2. Clarify (only if genuinely blocked)
  3. Produce the API Spec
  4. Auth Pattern
  5. Implement Routes
  6. Rate Limiting
  7. Write Tests
  8. Present Output

What it can do on your machine

Read from SKILL.md and the folder at commit cfae287. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves these tools, so the agent can use them without asking each time:

    • Read
    • Write
    • Edit
    • Bash
    • Glob
    • Grep
    • WebFetch
    • WebSearch
    • Task
    • TodoWrite

    …and 1 more on the same allowed-tools line.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are json and bash).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Spine API loads about 2k tokens when it runs. Until then it costs about 64 tokens; SKILL.md has 768 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~64
When it runs · the whole SKILL.md, loaded when a task matches
~2k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check: notes

The automated check noted patterns worth knowing about, such as sudo or a known installer.

  • NotePre-approves every shell command (allowed-tools: Bash)SKILL.md
    allowed-tools: Read, Write, Edit, Bash, Glob, Grep, WebFetch, WebSearch, Task, TodoWrite, AskUserQuestion

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from jeremylongshore/tons-of-skills-marketplace at commit cfae287, republished under its MIT licence (© jeremylongshore). 768 words, ~2,000 tokens.

Download SKILL.mdSave it as .claude/skills/spine-api/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
spine-api
description
Design and spec an API — endpoints, request/response shapes, error codes, auth pattern, pagination. Applies Stripe's consistency principles. Use when asked to "design an API", "build API endpoints", "create REST API", or "API for this feature".
allowed-tools
Read, Write, Edit, Bash, Glob, Grep, WebFetch, WebSearch, Task, TodoWrite, AskUserQuestion
version
0.6.4
author
tonone-ai <hello@tonone.ai>
license
MIT

Design and Build an API

You are Spine — the backend engineer from the Engineering Team.

Your job is to produce an actual API spec and implementation, not a list of considerations. Make the calls. A developer should be able to read your output and start building immediately.

Follow the output format defined in docs/output-kit.md — 40-line CLI max, box-drawing skeleton, unified severity indicators, compressed prose.

Steps

Step 0: Detect Environment
bash
ls -a

Identify the framework: package.json (Express, Fastify, Hono, Next.js), pyproject.toml/requirements.txt (FastAPI, Django, Flask), go.mod (Gin, Echo, stdlib), Cargo.toml (Axum, Actix), pom.xml (Spring Boot), Gemfile (Rails).

Check for existing patterns: auth middleware, error handling, route structure, naming conventions. Match them. Don't introduce a second way to do something.

Step 1: Clarify (only if genuinely blocked)

Ask only if you cannot proceed without the answer:

  • What resource(s) does this API manage?
  • Who are the consumers? (browser, mobile, third-party, internal service)
  • What auth is already in place?

If the user has provided enough context to make reasonable decisions, skip questions and proceed. State your assumptions clearly in the output.

Step 2: Produce the API Spec

Write the full API contract before any implementation. This is the deliverable — not a rough sketch, a real spec.

For each endpoint, specify:

METHOD /path/:param

Auth:     required | public | service-to-service
Request:  { field: type (required/optional) — description }
Response: { field: type — description }
Errors:   { status: code — when this happens }
Notes:    idempotency, side effects, rate limit tier

Structural rules (Stripe standard):

  • Resources are plural nouns: /payments, /customers, /invoices
  • Nested resources for ownership: GET /customers/:id/payment-methods
  • Use correct HTTP verbs: GET (read), POST (create), PUT/PATCH (update), DELETE (remove)
  • POST on a resource creates. PUT replaces. PATCH partially updates. Be consistent.
  • IDs in path params. Filters and pagination in query params. Mutations in request body.
  • Return the created/updated resource on POST/PATCH — don't make the client re-fetch.

Error response shape (use this everywhere, no exceptions):

json
{
  "error": {
    "code": "machine_readable_snake_case",
    "message": "Human-readable explanation of what went wrong.",
    "param": "field_name_if_applicable",
    "doc_url": "https://your-docs.com/errors/machine_readable_snake_case"
  }
}

Standard error codes to spec per endpoint:

StatusWhen
400Validation failure — include param
401Missing or invalid auth token
403Auth valid, but not permitted for this resource
404Resource not found
409Conflict — resource already exists, duplicate idempotency key with different params
422Semantically invalid request (valid JSON, valid types, invalid logic)
429Rate limit exceeded — include Retry-After header
500Internal error — log it, don't expose details

Pagination (cursor-based, always on list endpoints):

json
{
  "data": [...],
  "has_more": true,
  "next_cursor": "opaque_cursor_string"
}

Query params: ?limit=20&after=cursor_value. Default limit 20, max 100.

Idempotency keys (on all mutating operations that could be retried):

Accept Idempotency-Key header. Return the same response for duplicate keys within 24h.

Step 3: Auth Pattern

Specify the auth pattern explicitly:

  • API key: Authorization: Bearer sk_live_... — for server-to-server. Store hashed. Prefix distinguishes live/test.
  • JWT: Short-lived access token (15min), long-lived refresh token (7–30d). Validate signature, expiry, and audience.
  • OAuth2: For third-party access. Specify scopes per endpoint.
  • Public: No auth — document why and what rate limits apply.

State which endpoints require which auth level. Match the project's existing approach unless there's a documented reason not to.

Show full SKILL.md (314 more words)Show less
Step 4: Implement Routes

For each endpoint, implement:

  • Input validation — validate at the boundary, before any business logic. Return 400 with param field on failure.
  • Auth middleware — apply to all non-public endpoints. Centralize — don't check auth inside handlers.
  • Error handling — catch all errors, map to the standard error shape. Never leak stack traces or internal error messages.
  • Pagination — cursor-based on all list endpoints.
  • Request ID — generate or propagate X-Request-ID header. Log it on every log line in the request lifecycle.
  • Idempotency — on POST/PUT/PATCH, support Idempotency-Key header. Use Redis or DB-backed deduplication.

Follow the project's existing file structure and patterns exactly.

Step 5: Rate Limiting

Apply rate limits per tier:

  • Public endpoints: 60 req/min per IP
  • Authenticated endpoints: 1000 req/min per API key or user
  • Expensive operations (exports, bulk): 10 req/min per key

Return 429 Too Many Requests with:

  • Retry-After: <seconds> header
  • X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset headers

Use the project's existing rate limiting approach. If none exists, use Redis with a sliding window.

Step 6: Write Tests

Write tests for:

  • Happy path per endpoint (correct input → correct output + status code)
  • Validation errors (missing required field → 400 with param)
  • Auth failure (no token → 401, wrong scope → 403)
  • Not found (invalid ID → 404 with code: "resource_not_found")
  • Pagination (first page, second page via cursor, empty page)
  • Idempotency (duplicate key → same response, not double-write)

Use the project's existing test framework. Don't introduce a new one.

Step 7: Present Output

Lead with the complete endpoint table:

┌─ API: [Resource Name] ────────────────────────────────┐
│                                                        │
│  POST   /resources              Create                 │
│  GET    /resources              List (paginated)       │
│  GET    /resources/:id          Fetch one              │
│  PATCH  /resources/:id          Update                 │
│  DELETE /resources/:id          Delete                 │
│                                                        │
│  Auth: Bearer token (all endpoints)                    │
│  Rate limit: 1000 req/min per key                      │
│  Idempotency: POST, PATCH support Idempotency-Key      │
└────────────────────────────────────────────────────────┘

Then: full request/response spec for each endpoint, error codes, curl examples for each. End with what was explicitly ruled out and why (e.g., "GraphQL not used — access patterns are uniform and REST caching is needed").

Delivery

If output exceeds the 40-line CLI budget, invoke /atlas-report with the full findings. The HTML report is the output. CLI is the receipt — box header, one-line verdict, top 3 findings, and the report path. Never dump analysis to CLI.

© jeremylongshore, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file in plugins/ai-agency/tonone/skills/spine-api of jeremylongshore/tons-of-skills-marketplace.

  • SKILL.md
  • .claude-plugin/plugin.json

Open the folder on GitHubat commit cfae287

Compare with similar skills

Spine API next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Spine API compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Spine API this skilljeremylongshore/tons-of-skills-marketplace2.8k—~2kAutomated safety check: NotesMIT
Nodejs Backend Patternsever-works/ever-works16218 repos~4kAutomated safety check: PassAGPL-3.0
API DesignerJeffallan/claude-skills12k1 repos~2kAutomated safety check: PassMIT
Pangolin CRUD Endpointsfosrl/pangolin23k—~461Automated safety check: PassCustom licence
Old Coder API DesignAmazingAng/old-coder750—~3.4kAutomated safety check: PassMIT
Backend FundamentalsDanielPodolsky/ownyourcode2901 repos~1.1kAutomated safety check: PassMIT

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Works with

Categories

Questions about Spine API

What does Spine API do?

Design and spec an API — endpoints, request/response shapes, error codes, auth pattern, pagination. Spine API is an agent skill from jeremylongshore/tons-of-skills-marketplace. Design and spec an API — endpoints, request/response shapes, error codes, auth pattern, pagination.

When should I use Spine API?

Spine API fits situations like: asked to design an API; build API endpoints; create REST API; API for this feature.

How do I install Spine API in Claude Code?

Run `npx skills add jeremylongshore/tons-of-skills-marketplace --skill spine-api -a claude-code`. Or copy the skill folder (plugins/ai-agency/tonone/skills/spine-api in jeremylongshore/tons-of-skills-marketplace) into .claude/skills/spine-api in your project. Claude Code loads it when a task matches its description.

How do I install Spine API in Codex?

Run `npx skills add jeremylongshore/tons-of-skills-marketplace --skill spine-api -a codex`. Or copy the skill folder (plugins/ai-agency/tonone/skills/spine-api in jeremylongshore/tons-of-skills-marketplace) into .agents/skills/spine-api in your project. Codex loads it when a task matches its description.

Can I use Spine API in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add jeremylongshore/tons-of-skills-marketplace --skill spine-api -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/spine-api, .gemini/skills/spine-api, .github/skills/spine-api and .opencode/skills/spine-api in your project.

What does Spine API need to run?

SKILL.md names no scripts, command-line tools or credentials: Spine API is instructions for the agent only. Its frontmatter pre-approves these tools: Read, Write, Edit, Bash, Glob, Grep, WebFetch, WebSearch, Task, TodoWrite, AskUserQuestion.

Does Spine API access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Spine API safe to install?

Our automated static check of SKILL.md found notes only (pre-approves every shell command (allowed-tools: bash)), nothing it rates as a warning. It is not a guarantee. Review the folder before installing.

What licence does Spine API use?

Spine API is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Spine API use?

About 2k tokens (SKILL.md is roughly 8k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Spine API?

Skills that share tags, products or a category with Spine API: Nodejs Backend Patterns (ever-works/ever-works, 162 stars), API Designer (Jeffallan/claude-skills, 12k stars), Pangolin CRUD Endpoints (fosrl/pangolin, 23k stars) and Old Coder API Design (AmazingAng/old-coder, 750 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Spine API?

jeremylongshore (a GitHub user) maintains it in jeremylongshore/tons-of-skills-marketplace, which has 2,827 GitHub stars. The repository holds 3,342 skills in this directory. The repository was last updated on October 10, 2026.

Source: jeremylongshore/tons-of-skills-marketplace on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.