Fact Checking

What to Verify

• Claims about external tools/libraries
• Version numbers and API details
• Quotes and attributions
• Technical specifications
• Links match what's claimed in text
• Configuration examples (file paths, formats, options)
• Performance claims (optimization suggestions, benchmark numbers)

Process

1. User directs what to check

   • "Check the Redis claim in paragraph 3"
   • "Verify the Vagrant version requirements"
   • "Is the systemd behavior I described accurate?"

2. Fetch the source

   • Use web_fetch to get referenced documentation
   • Read official docs, not secondary sources when possible

3. Compare claim vs source

   • Does the claim match what the source says?
   • Is version information current?
   • Are quotes/code examples accurate?

4. Report findings

   • ✅ Verified: matches source
   • ⚠️ Outdated: source has changed
   • ❌ Mismatch: claim doesn't match source
   • 🚨 Hallucinated: config format/option doesn't exist in docs

Configuration Examples - Special Scrutiny

CRITICAL: Configuration examples are high-risk for hallucination. Before approving any config:

1. Verify the file path exists in official docs

   • .tool-name/config.yml - does this file format exist?
   • config/settings.json - is this the documented path?

2. Verify the configuration options

   • Are the option names exactly as documented?
   • Are the data types correct (array vs object vs string)?
   • Are nested paths correct?

3. Check for deprecated formats

   • Has the config format changed in recent versions?
   • Are we showing old patterns that no longer work?

4. Common hallucination patterns to watch for:

   • Inventing .hidden-dir/config.yml files
   • Creating YAML configs when tool uses TOML or JSON
   • Mixing up config locations (LSP init_options vs separate config files)
   • Assuming config file exists because directory exists (e.g., .ruby-lsp/ ≠ .ruby-lsp/config.yml)

Red flags:

• "You can configure X via some/path.yml" without a documentation link
• Config examples with TODO(@claude) markers still in them
• Performance claims without measurements ("this reduces time by 50%")

Not Exhaustive

This is targeted checking, not an audit of every claim. User points to specific sections they want verified.

Example Workflow

User: "Check if I got the LightDM systemd behavior right in the 'Display Manager Symlink' section"

Action:

1. Fetch systemd documentation on service types
2. Fetch LightDM documentation if available
3. Compare claim about "static" service type
4. Report: Verified/Mismatch/Unclear

Response Format

**Checked**: LightDM systemd service behavior

✅ **Verified**: LightDM is indeed a "static" unit type requiring explicit symlink to display-manager.service

Source: systemd.unit(5) man page confirms static units cannot be enabled without symlinks.

**Note**: Minor point - the systemd docs use slightly different terminology but your explanation is accurate.

Tools

• web_fetch for documentation
• Always cite sources checked
• Focus on technical accuracy, not writing style