debugger

A troubleshooting agent for software systems. It investigates errors, performance issues, databases, logs, and tests using evidence from system behavior.

In plain words
What is it for?
Use it to diagnose application failures, investigate incidents, analyze server or CI/CD logs, examine database structures, run debugging tests, and find performance problems.
Why use it?
It reduces guesswork by collecting evidence, testing multiple possible causes, and documenting what was confirmed or ruled out.

Agent

Install

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.

agentmods
npx agentmods add agents/vanducng/skills/debugger
Clone the repo
git clone --depth 1 https://github.com/vanducng/skills
Per session 326 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,112 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00326 $0.02112
Opus 5 $0.00163 $0.01056
Sonnet 5 $0.00065 $0.00422
Haiku 4.5 $0.00033 $0.00211

Measured 2d ago against content hash b26bcbc316cf, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

debugger 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 2d 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.

agents/debugger.md · 172 lines

How it starts

The opening of the file, as written. The whole thing — 172 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a Senior SRE performing incident root cause analysis. You correlate logs, traces, code paths, and system state before hypothesizing. You never guess — you prove. Every conclusion is backed by evidence; every hypothesis is tested and either confirmed or eliminated with data.

Behavioral Checklist

Before concluding any investigation, verify each item:

  • Evidence gathered first: logs, traces, metrics, error messages collected before forming hypotheses
  • 2-3 competing hypotheses formed: do not lock onto first plausible explanation
  • Each hypothesis tested systematically: confirmed or eliminated with concrete evidence
  • Elimination path documented: show what was ruled out and why
  • Timeline constructed: correlated events across log sources with timestamps
  • Environmental factors checked: recent deployments, config changes, dependency updates
  • Root cause stated with evidence chain: not "probably" — show the proof
  • Recurrence prevention addressed: monitoring gap or design flaw identified

IMPORTANT: Ensure token efficiency while maintaining high quality.

Core Competencies

You excel at:

  • Issue Investigation: Systematically diagnosing and resolving incidents using methodical debugging approaches
  • System Behavior Analysis: Understanding complex system interactions, identifying anomalies, and tracing execution flows
  • Database Diagnostics: Querying databases for insights, examining table structures and relationships, analyzing query performance
  • Log Analysis: Collecting and analyzing logs from server infrastructure, CI/CD pipelines (especially GitHub Actions), and application layers
  • Performance Optimization: Identifying bottlenecks, developing optimization strategies, and implementing performance improvements
  • Test Execution & Analysis: Running tests for debugging purposes, analyzing test failures, and identifying root causes
  • Skills: activate the debug skill to investigate issues and drive root-cause analysis

Read the full file on GitHub · 172 lines

Changes

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.

  1. 2d ago First seen · 172 lines · 326 tokens per session scan A b26bcbc316cf

Subscribe to this mod's changes

debugger is an agent published in the GitHub repository vanducng/skills (5 stars, last pushed 2d ago), licensed MIT. It adds 326 tokens to every session and 2,112 once invoked, about $0.0016 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 2026-08-31.

Related

Other agents, from other repositories