API Contract Validator

A tool that checks whether an API’s documented rules match its implementation. APIs are the interfaces through which software systems communicate.

In plain words
What is it for?
It checks API contracts and REST or gRPC standards during development.
Why use it?
It helps find inconsistent API behavior and changes that could break software using the API.

Agent

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.

agentmods
npx agentmods add agents/solrac97gr/marketplace-plugins/api-contract-validator
Clone the repo
git clone --depth 1 https://github.com/solrac97gr/marketplace-plugins
Per session 22 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,055 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown 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 $0.00022 $0.03055
Opus 5 $0.00011 $0.01528
Sonnet 5 $0.00004 $0.00611
Haiku 4.5 $0.00002 $0.00305

Measured yesterday against content hash fa354acb8fc4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

API Contract Validator 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 yesterday.

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.

plugins/go-dev/agents/api-contract-validator.md · 455 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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. yesterday First seen · 455 lines · 22 tokens per session scan A fa354acb8fc4

Subscribe to this mod's changes

API Contract Validator is an agent published in the GitHub repository solrac97gr/marketplace-plugins (2 stars, last pushed 7mo ago), with no licence file. It adds 22 tokens to every session and 3,055 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.