agentmods.dev

MCPPythonDemo: Skill for Claude Code

.squad/skills/mcp-stdio-parity-testing/SKILL.md

mcp-stdio-parity-testing is a skill for Claude Code, Codex from alonf/MCPPythonDemo. It costs 0 tokens per session (286 once invoked), scanned A, original, MIT.

A testing pattern for checking a Python MCP server that communicates over standard input and output. It also covers testing an LLM client, including TDD-style negative cases, where TDD means testing expected behavior before or alongside implementation.

In plain words
What is it for?
Use it to test server initialization, successful and failed tool calls, `/proc` system reads, fake-model tool workflows, and command-line behavior when credentials are absent.
Why use it?
It catches broken startup, tool-discovery, invalid-tool, system-read, and missing-credential behavior before review or release.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

This is alonf/MCPPythonDemo's own configuration. It tells Claude Code and Codex how to work on MCPPythonDemo 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 MCPPythonDemo configures →

not rated 0repo 6mo ago A scan 0 tokens original MIT
View source ↗ alonf/MCPPythonDemo
Reuse

Borrowing it

Nothing to install: this file belongs to alonf/MCPPythonDemo. 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/alonf/MCPPythonDemo/master/.squad/skills/mcp-stdio-parity-testing/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/alonf/MCPPythonDemo

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 mcp-stdio-parity-testing

README.md
[![agentmods](https://agentmods.dev/badge/skills/alonf/mcppythondemo/mcp-stdio-parity-testing/github.svg)](https://agentmods.dev/skills/alonf/mcppythondemo/mcp-stdio-parity-testing)
Your own site
<a href="https://agentmods.dev/skills/alonf/mcppythondemo/mcp-stdio-parity-testing"><img src="https://agentmods.dev/badge/skills/alonf/mcppythondemo/mcp-stdio-parity-testing/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 mcp-stdio-parity-testing

Your own site · 80×15
<a href="https://agentmods.dev/skills/alonf/mcppythondemo/mcp-stdio-parity-testing"><img src="https://agentmods.dev/badge/skills/alonf/mcppythondemo/mcp-stdio-parity-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 286 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 $0.00000 $0.00286
Opus 5.5 $0.00000 $0.00114
Sonnet 5.5 $0.00000 $0.00057
Haiku 4.5 $0.00000 $0.00029

Measured 2mo ago against content hash 18a36d6855fb, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

mcp-stdio-parity-testing 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 2mo 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.

.squad/skills/mcp-stdio-parity-testing/SKILL.md · 39 lines

What it actually says

MCP STDIO Parity Testing Skill

When to use

Use this pattern when a repo needs reviewer-grade validation for:

  • a Python MCP stdio server
  • a lecture/demo parity path against another reference implementation
  • a client-side LLM workflow that should fail cleanly when credentials are missing

Pattern

  1. Validate the server with the official SDK client

    • start the server with StdioServerParameters
    • run initialize
    • assert tool discovery
    • call the target tool on happy path
    • call an invalid tool and confirm an error payload, not a crash

  2. Add negative-path unit coverage around live system reads

    • patch /proc readers
    • require zero/fallback payloads instead of exceptions

  3. Split client validation into two lanes

    • fake-model/unit lane for deterministic tool-calling orchestration
    • real CLI lane with credentials stripped so missing-config messaging is tested exactly as users see it

  4. Make smoke output human-readable

    • print the live server payload
    • print the validated client failure message
    • keep transport details out of the final QA summary

Files in this repo that follow the pattern

  • tests/test_m1_smoke.py
  • tests/test_system_info.py
  • tests/test_client.py
  • scripts/smoke_test.py
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. 2mo ago First seen · 39 lines · 0 tokens per session scan A 18a36d6855fb

Subscribe to this mod's changes

mcp-stdio-parity-testing is a skill published in the GitHub repository alonf/MCPPythonDemo (0 stars, last pushed 6mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 286 tokens. 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.

TDDTesting
Related

mcp-stdio-parity-testing compared with skills from other repositories

mcp-stdio-parity-testing next to 6 skills from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
mcp-stdio-parity-testingalonf/MCPPythonDemoSkill06mo agoMITA0Claude Code, Codex
engram-testing-coverageGentleman-Programming/engramSkill7.8kyesterdayMITA25Claude Code, Codex
principle-test-behavior-not-implementationmichael-denyer/pstack-claudeSkill4.1kyesterdayMITA50Claude Code
tddcodewithmukesh/dotnet-claude-kitSkill8052d agoMITA81Claude Code
nw-ddd-eventsourcingnWave-ai/nWaveSkill631yesterdayMITA38Claude Code
nw-fp-clojurenWave-ai/nWaveSkill631yesterdayMITA25Claude Code
nw-leanux-methodologynWave-ai/nWaveSkill631yesterdayMITA37Claude Code