contract-author

contract-author is a skill for Claude Code from ivy00johns/Skill-Madness. It costs 170 tokens per session (2,999 once invoked), scanned A, original, MIT.

A tool for writing machine-readable agreements about APIs, shared data, types, and events before a multi-agent software project is implemented.

In plain words
What is it for?
Use it in the contract-first phase of a multi-agent build, before implementation agents are started.
Why use it?
These contracts give separate coding agents the same expectations for endpoints, data shapes, and storage, reducing integration mismatches.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Part of the skill-madness plugin — 80 skills shipped together

Good fit Use it in the contract-first phase of a multi-agent build, before implementation agents are started.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ivy00johns/skill-madness/contract-author
Install

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.

Any agent
npx skills add ivy00johns/Skill-Madness --skill contract-author
Clone the repo
git clone --depth 1 https://github.com/ivy00johns/Skill-Madness

Made for: Claude Code.

Or install skill-madness, the plugin that ships this one along with the rest of its 80 skills.

Wrote 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.

agentmods badge for contract-author

README.md
[![agentmods](https://agentmods.dev/badge/skills/ivy00johns/skill-madness/contract-author/github.svg)](https://agentmods.dev/skills/ivy00johns/skill-madness/contract-author)
Your own site
<a href="https://agentmods.dev/skills/ivy00johns/skill-madness/contract-author"><img src="https://agentmods.dev/badge/skills/ivy00johns/skill-madness/contract-author/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.

agentmods 80×15 button for contract-author

Your own site · 80×15
<a href="https://agentmods.dev/skills/ivy00johns/skill-madness/contract-author"><img src="https://agentmods.dev/badge/skills/ivy00johns/skill-madness/contract-author.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 170 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,999 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00170 $0.02999
Opus 5 $0.00085 $0.01499
Sonnet 5 $0.00034 $0.00600
Haiku 4.5 $0.00017 $0.00300

Measured 9d ago against content hash 5b396f17543b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

contract-author 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 9d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (references/pydantic-template.py, references/typescript-template.ts), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/contracts/contract-author/SKILL.md · 240 lines

How it starts

The opening of the file, as written. The whole thing — 240 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Contract Author

Tradeoff: Biases toward upfront design over fast iteration. For prototypes, skip contracts and use direct module imports.

When this skill applies

This skill assumes a contract-first multi-agent build model:

  • An orchestrator dispatches role-agents in parallel
  • Each role-agent consumes a machine-readable contract from /contracts/
  • qe-agent gates the build via qa-report.json

For single-agent or ad-hoc work, this skill is not the right tool.

Generate machine-readable integration contracts before any implementation begins. Contracts are the foundation of reliable multi-agent builds — specification problems cause ~42% of multi-agent failures.

Role

You are the contract author. You create the shared types, API contracts, and data layer contracts that implementation agents build against. You work during the orchestrator's Phase 4, before any implementation agent is spawned.

Why Contracts Matter

Without contracts, agents independently invent their own endpoint URLs, response shapes, type definitions, and storage semantics. The result: two implementations that technically work in isolation but fail at integration. Contracts eliminate this by defining the interfaces upfront.

Process

0a. Read project config — docs/agents/contract-format.md

Before extracting entities or touching a template, check for docs/agents/contract-format.md. That file (written by /setup-project-skills) declares the repo's preferred contract format and the conventional output paths for it. When present, use it as the source of truth for the rest of this skill:

  • It names one format: OpenAPI, Pydantic, TypeScript, or JSON Schema.
  • It names the output directory and filename convention (e.g. contracts/openapi/<name>.openapi.yaml).
  • It may name per-agent consumption notes (which agent generates types from the spec, which agent gates conformance).

If the file is present, skip the "Pick the format that matches the project's primary language" choice in step 1 and use the declared one. If the file is missing, fall back to detecting from the project's primary language (TS → TypeScript, Python → Pydantic, mixed/HTTP-heavy → OpenAPI, event-driven → JSON Schema) and surface one prompt: "This repo isn't configured yet. Using <detected> for this contract; run /setup-project-skills to make the choice durable." Do not silently default — the contract format choice is sticky and gets re-derived every time without the config.

Read the full file on GitHub · 240 lines

Files

What ships with it

6 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.

Changes

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.

  1. 9d ago First seen · 240 lines · 170 tokens per session scan A 5b396f17543b

Subscribe to this mod's changes

contract-author is a skill published in the GitHub repository ivy00johns/Skill-Madness (11 stars, last pushed today), licensed MIT. It adds 170 tokens to every session and 2,999 once invoked, about $0.0009 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 2026-08-30.

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