Borrowing it
Nothing to install: this file belongs to taurgis/sfcc-dev-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.
curl -O https://raw.githubusercontent.com/taurgis/sfcc-dev-mcp/main/.github/skills/mcp-yaml-testing/SKILL.mdgit clone --depth 1 https://github.com/taurgis/sfcc-dev-mcpWrote 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.
[](https://agentmods.dev/skills/taurgis/sfcc-dev-mcp/mcp-yaml-testing)<a href="https://agentmods.dev/skills/taurgis/sfcc-dev-mcp/mcp-yaml-testing"><img src="https://agentmods.dev/badge/skills/taurgis/sfcc-dev-mcp/mcp-yaml-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.
<a href="https://agentmods.dev/skills/taurgis/sfcc-dev-mcp/mcp-yaml-testing"><img src="https://agentmods.dev/badge/skills/taurgis/sfcc-dev-mcp/mcp-yaml-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 12 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium MCP Rug Pull · line 16 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 19 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 20 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 27 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 36 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 115 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 118 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 125 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 128 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 129 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 132 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 135 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00044 | $0.01019 |
| Opus 5 | $0.00022 | $0.00509 |
| Sonnet 5 | $0.00009 | $0.00204 |
| Haiku 4.5 | $0.00004 | $0.00102 |
Grade A, and why
mcp-yaml-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 9d 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.
How it starts
The opening of the file, as written. The whole thing — 137 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MCP YAML Testing Skill
Use this skill when writing or debugging *.test.mcp.yml files for Model Context Protocol servers.
Golden Rule: Discovery First
CRITICAL: Before writing ANY YAML test, discover actual response formats:
# Test successful execution
npx aegis query [tool_name] '[valid_params]' --config "./aegis.config.docs-only.json"
# Test failure scenarios
npx aegis query [tool_name] '[invalid_params]' --config "./aegis.config.docs-only.json"
npx aegis query [tool_name] '' --config "./aegis.config.docs-only.json" # Empty params
Parameter Formats
Pipe Format (Recommended)
npx aegis query read_file 'path:test.txt' --config "./aegis.config.docs-only.json"
npx aegis query calculator 'operation:add|a:5|b:3' --config "./aegis.config.docs-only.json"
# Nested via dot notation
npx aegis query api_client 'config.host:localhost|config.port:8080' --config "./aegis.config.docs-only.json"
JSON Format (Complex Structures)
npx aegis query complex_tool '{"config": {"host": "localhost"}, "data": [1,2,3]}' --config "./aegis.config.docs-only.json"
Basic Test Structure
description: "Test suite description"
tests:
- it: "Test description"
request:
jsonrpc: "2.0"
id: "unique-id"
method: "tools/list" # or "tools/call"
params: {}
expect:
response:
jsonrpc: "2.0"
id: "unique-id"
result: {}
stderr: "toBeEmpty"
Common Pattern Reference
# TYPE VALIDATION
result:
tools: "match:type:array"
count: "match:type:number"
# STRING PATTERNS
result:
text: "match:contains:substring"
name: "match:startsWith:prefix"
pattern: "match:regex:\\d{4}-\\d{2}-\\d{2}" # Double-escape backslashes!
# ARRAY PATTERNS
result:
tools: "match:arrayLength:3"
tools:
match:arrayElements:
match:partial: # Flexible - only validate specified fields
name: "match:regex:^[a-z_]+$"
description: "match:contains:tool"
# NEGATION
result:
tools: "match:not:arrayLength:0"
text: "match:not:contains:error"
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.
- 9d ago First seen · 137 lines · 44 tokens per session scan A 199af4562d84
mcp-yaml-testing is a skill published in the GitHub repository taurgis/sfcc-dev-mcp (28 stars, last pushed 3d ago), licensed MIT. It adds 44 tokens to every session and 1,019 once invoked, about $0.0002 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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