mal-mcp: Skill for Claude Code

.agents/skills/prompt-check/SKILL.md

prompt-check is a skill for Claude Code, Codex from Grinv/mal-mcp. It costs 53 tokens per session (507 once invoked), scanned A, original, MIT.

A testing guide for MCP prompts, which are reusable requests exposed by an MCP server, using the real protocol and every supported argument combination.

In plain words
What is it for?
Use it to test prompts such as anime recommendations and seasonal overviews with missing, complete, and no-result inputs.
Why use it?
Static inspection can miss errors in how prompt arguments are handled. Live testing shows whether each prompt actually works when a client calls it.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

This is Grinv/mal-mcp's own configuration. It tells Claude Code and Codex how to work on mal-mcp 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 mal-mcp configures →

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is npx @modelcontextprotocol/inspector --cli node dist/index.js --method prompts/list.

Reuse

Borrowing it

Nothing to install: this file belongs to Grinv/mal-mcp. 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/Grinv/mal-mcp/main/.agents/skills/prompt-check/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/Grinv/mal-mcp

Made for: Claude Code, Codex.

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 prompt-check

README.md
[![agentmods](https://agentmods.dev/badge/skills/grinv/mal-mcp/prompt-check.svg)](https://agentmods.dev/skills/grinv/mal-mcp/prompt-check)
Your own site
<a href="https://agentmods.dev/skills/grinv/mal-mcp/prompt-check"><img src="https://agentmods.dev/badge/skills/grinv/mal-mcp/prompt-check.svg" alt="Measured on agentmods" height="20"></a>
Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 507 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 $0.00053 $0.00507
Opus 5 $0.00026 $0.00253
Sonnet 5 $0.00011 $0.00101
Haiku 4.5 $0.00005 $0.00051

Measured 6d ago against content hash b8e41e29545f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

prompt-check 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/prompt-check/SKILL.md · 39 lines

What it actually says

Prompt check — live-test every MCP Prompt argument combination

A static read comparing prompt text against tool names/params misses argument-handling bugs. Actually render every prompt through the real MCP protocol:

npx @modelcontextprotocol/inspector --cli node dist/index.js --method prompts/list
npx @modelcontextprotocol/inspector --cli node dist/index.js --method prompts/get \
  --prompt-name <name> --prompt-args key=value key2=value2

--prompt-args takes space-separated key=value pairs, not a JSON blob — the CLI rejects JSON with "Invalid parameter format".

For each of the three prompts, cover every combination of optional args, not just "all set" or "all omitted":

  • recommend_similar: no title (should ask which anime, not fail — confirm the client actually gets asked rather than the call erroring), title set to something real, title set to something with no search results.
  • seasonal_overview: neither season nor year, only season, only year, both together. Giving just one of season/year alone renders identically to giving neither ("the current season," no args passed to get_seasonal_anime) — this is correct, not a bug: get_seasonal_anime's own description says supplying only one is treated as omitting both (matches getSeason()'s p.year && p.season ? ... : "seasons/now" in src/clients/tenrai.ts), so the prompt mirrors the tool's own contract. Don't flag this from a source-only read of the prompt's branching alone — it resembles the "argument that's individually optional but breaks when given alone" bug class, but here the "breakage" is intended.
  • hidden_gems: no kind, kind=anime, kind=manga — each is a genuinely different branch (different top-list tool).
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 · 39 lines · 53 tokens per session scan A b8e41e29545f

Subscribe to this mod's changes

prompt-check is a skill published in the GitHub repository Grinv/mal-mcp (2 stars, last pushed 13d ago), licensed MIT. It adds 53 tokens to every session and 507 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 2026-08-31.

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