mcp-server-for-ynab: Skill for Claude Code

.agents/skills/contract-sync/SKILL.md

contract-sync is a skill for Claude Code from hs737/mcp-server-for-ynab. It costs 20 tokens per session (600 once invoked), scanned A, original, Apache-2.0.

A development workflow for keeping interface definitions, generated files, and tests in agreement. An interface definition describes how code, APIs, or tools accept and return data; generated files are produced from those definitions.

In plain words
What is it for?
Use it when changing request or response formats, HTTP routes, MCP tool schemas, OpenAPI or JSON Schema files, generated clients, prompt contracts, or related tests.
Why use it?
It helps prevent drift, where the documented or generated interface no longer matches the actual code. This is important when changing routes, data models, schemas, MCP tools, or public documentation.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: installed under .agents/ (shared by several agents); mentions AGENTS.md.

This is hs737/mcp-server-for-ynab's own configuration. It tells Claude Code how to work on mcp-server-for-ynab itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything mcp-server-for-ynab configures →

Part of the mcp-server-for-ynab plugin — 12 skills, 2 MCP servers shipped together

Reuse

Borrowing it

Nothing to install: this file belongs to hs737/mcp-server-for-ynab. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/hs737/mcp-server-for-ynab/master/.agents/skills/contract-sync/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/hs737/mcp-server-for-ynab

Made for: Claude Code.

Or install mcp-server-for-ynab, the plugin that ships this one along with the rest of its 12 skills, 2 MCP servers.

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-sync

README.md
[![agentmods](https://agentmods.dev/badge/skills/hs737/mcp-server-for-ynab/contract-sync.svg)](https://agentmods.dev/skills/hs737/mcp-server-for-ynab/contract-sync)
Your own site
<a href="https://agentmods.dev/skills/hs737/mcp-server-for-ynab/contract-sync"><img src="https://agentmods.dev/badge/skills/hs737/mcp-server-for-ynab/contract-sync.svg" alt="Measured on agentmods" height="20"></a>
Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 600 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 $0.00020 $0.00600
Opus 5 $0.00010 $0.00300
Sonnet 5 $0.00004 $0.00120
Haiku 4.5 $0.00002 $0.00060

Measured 6d ago against content hash 1063deb43c04, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

contract-sync 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.

.agents/skills/contract-sync/SKILL.md · 60 lines

How it starts

The opening of the file, as written. The whole thing — 60 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Contract Sync

Use this skill when the repo has any source-of-truth contract and derived artifacts such as OpenAPI, JSON Schema, generated clients, MCP tool schemas, or prompt/task contracts.

Use When

  • Changing HTTP routes or MCP tool inputs/outputs
  • Changing request or response shapes (Pydantic models, dataclasses, TypedDicts)
  • Changing schema-driven generated artifacts
  • Updating public interface docs
  • Updating codegen outputs
  • Reviewing drift between source and generated files

Read First

  • AGENTS.md (if present)
  • README.md and pyproject.toml ([project.scripts], [tool.*], optional dependency groups)
  • CONTRIBUTING.md if present and maintained
  • Contract-related docs in this repo (for example docs/api-strategy.md, docs/contract-discipline.md)
  • postman/ or OpenAPI under docs/api/, only if this repo maintains them
  • Generation scripts under scripts/ or tools/

Core Rules

  1. Identify the source of truth before editing anything.
    • Common patterns in Python repos: Pydantic (or similar) models; FastAPI/Starlette route signatures; hand-authored OpenAPI; JSON Schema; MCP tool parameter schemas derived from types or explicit definitions.
    • Derived artifacts (OpenAPI YAML, JSON Schema exports, generated clients, Postman collections) must be regenerated from that source unless the repo documents otherwise.
  2. Do not hand-edit generated artifacts unless the repo explicitly says to.
  3. Regenerate derived artifacts when the source changes, using commands in pyproject.toml, Makefile, uv run, poetry run, or documented in README.md / AGENTS.md.
  4. Commit source changes and generated changes together.
  5. Update docs that describe the public or shared contract surface.
  6. Ensure tests validate the actual interface (pytest, contract tests, schema snapshots)—not only internal mocks.

Workflow

  1. Determine whether the change affects a contract.
  2. Identify the hand-authored source and the generated outputs (pyproject.toml, CI config, repo docs).
  3. Update the source of truth (models, tool definitions, route handlers).
  4. Run the appropriate generation or export step.
  5. Update any relevant docs or examples.
  6. Run the relevant tests or checks.

Read the full file on GitHub · 60 lines

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. 6d ago First seen · 60 lines · 20 tokens per session scan A 1063deb43c04

Subscribe to this mod's changes

contract-sync is a skill published in the GitHub repository hs737/mcp-server-for-ynab (1 stars, last pushed 3d ago), licensed Apache-2.0. It adds 20 tokens to every session and 600 once invoked, about $0.0001 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 2026-08-31.

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