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 agentmods add skills/cosmicstack-labs/mercury-agent-skills/debugging-masterynpx skills add cosmicstack-labs/mercury-agent-skills --skill debugging-masterygit clone --depth 1 https://github.com/cosmicstack-labs/mercury-agent-skillsWrote 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/cosmicstack-labs/mercury-agent-skills/debugging-mastery)<a href="https://agentmods.dev/skills/cosmicstack-labs/mercury-agent-skills/debugging-mastery"><img src="https://agentmods.dev/badge/skills/cosmicstack-labs/mercury-agent-skills/debugging-mastery.svg" alt="Measured on agentmods" 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 | $0.00019 | $0.04087 |
| Opus 5 | $0.00010 | $0.02044 |
| Sonnet 5 | $0.00004 | $0.00817 |
| Haiku 4.5 | $0.00002 | $0.00409 |
Grade A, and why
debugging-mastery scanned grade A with 1 finding 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 6d 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
# 3. Reproduce with curl How it starts
The opening of the file, as written. The whole thing — 533 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Debugging Mastery
A structured approach to finding and fixing bugs systematically — from initial symptom to permanent resolution.
Core Principles
1. Understand Before You Fix
The biggest debugging mistake is applying a fix before understanding the root cause. Correlation is not causation. Always prove you understand why a bug happens before changing code.
2. Isolate Before You Investigate
Narrow the search space. A bug that manifests in 100 lines is harder to find than one isolated to 10 lines. Binary search the code, the data, and the environment.
3. Fix the Root Cause, Not the Symptom
Patching symptoms creates technical debt. Firefighting is necessary, but it should always be followed by a permanent fix that addresses the underlying systemic issue.
4. Make It Reproducible First
If you can't reproduce a bug reliably, you can't fix it. Invest in reproduction before investigation. A failing test is worth a thousand log statements.
Debugging Maturity Model
| Level | Approach | Tools | Prevention |
|---|---|---|---|
| 1: Reactive | Random printf guessing | console.log, print statements | No prevention |
| 2: Basic | Incremental investigation | Logging, basic breakpoints | Some error handling |
| 3: Structured | Scientific method applied | Debugger, log levels, metrics | Unit tests for found bugs |
| 4: Systematic | Root cause analysis documented | Distributed tracing, profilers | Regression tests for all bugs |
| 5: Proactive | Predictive monitoring | Observability platform, chaos engineering | Automated anomaly detection |
Target: Level 3+ for individual developers. Level 4+ for teams.
Actionable Guidance
The Scientific Method of Debugging
┌─────────────┐ ┌──────────────┐ ┌──────────────┐ ┌─────────────┐ ┌──────────────┐
│ Observe │ ──► │ Hypothesize │ ──► │ Predict │ ──► │ Experiment │ ──► │ Conclude │
│ Symptom │ │ Root Cause │ │ Outcome │ │ Test Fix │ │ Verified? │
└─────────────┘ └──────────────┘ └──────────────┘ └─────────────┘ └──────────────┘
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.
- 6d ago First seen · 533 lines · 19 tokens per session scan A 9385aeed5488
debugging-mastery is a skill published in the GitHub repository cosmicstack-labs/mercury-agent-skills (471 stars, last pushed 11d ago), licensed MIT. It adds 19 tokens to every session and 4,087 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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