Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add Guild-Agents/guild --skill debuggit clone --depth 1 https://github.com/Guild-Agents/guildWrote 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/guild-agents/guild/debug)<a href="https://agentmods.dev/skills/guild-agents/guild/debug"><img src="https://agentmods.dev/badge/skills/guild-agents/guild/debug/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/guild-agents/guild/debug"><img src="https://agentmods.dev/badge/skills/guild-agents/guild/debug.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00033 | $0.01215 |
| Opus 5.5 | $0.00013 | $0.00486 |
| Sonnet 5.5 | $0.00007 | $0.00243 |
| Haiku 4.5 | $0.00003 | $0.00121 |
Grade A, and why
debug 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 1mo 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 — 146 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Systematic Debugging
Random fixes waste time and create new bugs. Quick patches mask underlying issues.
Core principle: ALWAYS find root cause before attempting fixes.
Usage
/debug
Invoke this skill when encountering any bug, test failure, or unexpected behavior. Follow the four phases in order.
When to use
- Test failures
- Bugs in production
- Unexpected behavior
- Performance problems
- Build failures
- Integration issues
Use this ESPECIALLY when:
- Under time pressure (emergencies make guessing tempting)
- "Just one quick fix" seems obvious
- You've already tried multiple fixes
- Previous fix didn't work
The Iron Law
NO FIXES WITHOUT ROOT CAUSE INVESTIGATION FIRST
If you haven't completed Phase 1, you cannot propose fixes.
The Four Phases
Complete each phase before proceeding to the next.
Phase 1: Root Cause Investigation
BEFORE attempting ANY fix:
-
Read Error Messages Carefully
- Don't skip past errors or warnings
- Read stack traces completely
- Note line numbers, file paths, error codes
-
Reproduce Consistently
- Can you trigger it reliably?
- What are the exact steps?
- If not reproducible, gather more data — don't guess
-
Check Recent Changes
- What changed that could cause this?
- Git diff, recent commits
- New dependencies, config changes
-
Gather Evidence in Multi-Component Systems
- Log what data enters each component boundary
- Log what data exits each component boundary
- Verify environment/config propagation
- Run once to gather evidence showing WHERE it breaks
- THEN investigate that specific component
-
Trace Data Flow
- Where does the bad value originate?
- What called this with the bad value?
- Keep tracing up until you find the source
- Fix at source, not at symptom
Phase 2: Pattern Analysis
- Find Working Examples — locate similar working code in the same codebase
- Compare Against References — read reference implementations COMPLETELY, don't skim
- Identify Differences — list every difference between working and broken, however small
- Understand Dependencies — what components, settings, environment does it need?
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.
- 1mo ago First seen · 146 lines · 33 tokens per session scan A b8e44fcf2a6f
debug is a skill published in the GitHub repository Guild-Agents/guild (4 stars, last pushed 3mo ago), licensed MIT. It adds 33 tokens to every session and 1,215 once invoked, about $0.0001 per session on Opus 5.5. 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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