How do I install the Cross Checker skill?

Run npx skillmds add majiayu000/cross-checker in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Cross Checker safe to use?

This skill has not completed SkillMD's automated safety review yet. Capability flags: reads secrets. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Cross Checker?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Cross Checker free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Cross Checker?

majiayu000 (@majiayu000) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Cross Checker by majiayu000 — Agent Skill

Name: Cross Checker
Rating: 4.666666666666667 (3 reviews)
Author: majiayu000

File contents

Cross-Checker: Multi-Angle Verification

Never trust a single source. Verify from at least two independent angles before accepting a claim as fact.

The cross-checking method

For any claim, check it against multiple sources:

Source 1: The code itself

Read the actual file. What does the code do? This is the strongest evidence.

Source 2: Tests

What do the tests expect? Tests reveal intended behavior. If a test expects validateToken to return false for expired tokens, that's the designed behavior.

Source 3: Git history

What was the original intent? Git blame and commit messages reveal why code was written. "commit abc123: fix token expiration check to reject tokens older than 24h"

Source 4: Documentation

README, comments, JSDoc, API docs. Do they match the code? If docs say one thing and code does another, the code is truth but the discrepancy matters.

Source 5: Configuration

Config files, environment variables, feature flags. Runtime behavior may differ from what the code looks like.

Source 6: Dependencies

Package versions, API compatibility, deprecated features. A function might exist in the code but be broken due to a dependency update.

Minimum verification standard

Situation	Minimum angles needed
Stating a fact to the user	1 (read the code)
Recommending a code change	2 (code + tests or git history)
Security-related claims	3 (code + tests + docs/config)
Production deployment advice	3 (code + config + git history)
"This is safe to delete"	3 (code + grep for references + tests)

Cross-check workflow

Make the initial claim based on what you know
Identify which type of claim it is (fact, recommendation, security)
Check the required number of angles
If sources agree: proceed with confidence
If sources disagree: flag the discrepancy, investigate further
If sources are insufficient: say so, suggest how to get more evidence

Red flags that demand cross-checking

"This function is never called" (grep the entire codebase first)
"This file isn't used anymore" (check imports, configs, build scripts)
"This dependency can be removed" (check all import statements)
"This environment variable isn't needed" (check all config files and deploy scripts)
"This test is redundant" (check what specific edge case it covers)

---name: cross-checkerdescription: Verify every claim from multiple independent angles -- code, docs, tests, git history. Use when you need high confidence that something is correct before acting on it.--- # Cross-Checker: Multi-Angle Verification Never trust a single source. Verify from at least two independent angles before accepting a claim as fact. ## The cross-checking method For any claim, check it against multiple sources: ### Source 1: The code itself Read the actual file. What does the code do? This is the strongest evidence. ### Source 2: Tests What do the tests expect? Tests reveal intended behavior. If a test expects validateToken to return false for expired tokens, that's the designed behavior. ### Source 3: Git history What was the original intent? Git blame and commit messages reveal why code was written. "commit abc123: fix token expiration check to reject tokens older than 24h" ### Source 4: Documentation README, comments, JSDoc, API docs. Do they match the code? If docs say one thing and code does another, the code is truth but the discrepancy matters. ### Source 5: Configuration Config files, environment variables, feature flags. Runtime behavior may differ from what the code looks like. ### Source 6: Dependencies Package versions, API compatibility, deprecated features. A function might exist in the code but be broken due to a dependency update. ## Minimum verification standard | Situation | Minimum angles needed | |-----------|----------------------| | Stating a fact to the user | 1 (read the code) | | Recommending a code change | 2 (code + tests or git history) | | Security-related claims | 3 (code + tests + docs/config) | | Production deployment advice | 3 (code + config + git history) | | "This is safe to delete" | 3 (code + grep for references + tests) | ## Cross-check workflow 1. Make the initial claim based on what you know 2. Identify which type of claim it is (fact, recommendation, security) 3. Check the required number of angles 4. If sources agree: proceed with confidence 5. If sources disagree: flag the discrepancy, investigate further 6. If sources are insufficient: say so, suggest how to get more evidence ## Red flags that demand cross-checking - "This function is never called" (grep the entire codebase first) - "This file isn't used anymore" (check imports, configs, build scripts) - "This dependency can be removed" (check all import statements) - "This environment variable isn't needed" (check all config files and deploy scripts) - "This test is redundant" (check what specific edge case it covers)

Frequently asked questions