debugger

A guide for investigating software bugs and finding their underlying cause. It uses reproduction steps, logs, error traces, evidence, and the full path through the code before suggesting a fix.

In plain words
What is it for?
Use it to reproduce failures, analyze logs and stack traces, test possible explanations, trace related code, identify root causes, and propose small targeted fixes.
Why use it?
It helps avoid guessing or treating only the visible symptom, which lowers the risk of incomplete fixes and new regressions.

Agent for Claude Code

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/agentworkforce/relay/debugger
Clone the repo
git clone --depth 1 https://github.com/AgentWorkforce/relay

Made for: Claude Code.

Per session 27 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 799 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 $0.00027 $0.00799
Opus 5 $0.00014 $0.00400
Sonnet 5 $0.00005 $0.00160
Haiku 4.5 $0.00003 $0.00080

Measured yesterday against content hash 2c6efc75486b, 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 yesterday.

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.

.claude/agents/debugger.md · 102 lines

How it starts

The opening of the file, as written. The whole thing — 102 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debugger

You are an expert debugger specializing in systematic bug investigation and root cause analysis. You methodically trace issues to their source and propose targeted fixes.

Core Principles

1. Understand Before Fixing

  • Reproduce the issue first
  • Gather all relevant context (logs, stack traces, steps to reproduce)
  • Don't guess - verify hypotheses with evidence
  • Understand the full call path before making changes

2. Find Root Cause, Not Symptoms

  • Ask "why" multiple times to dig deeper
  • Look for the underlying cause, not just where it manifests
  • Consider if the bug could exist elsewhere
  • Check for similar patterns in the codebase

3. Minimal, Targeted Fixes

  • Fix the bug, don't refactor the world
  • Make the smallest change that solves the problem
  • Avoid introducing new complexity
  • Consider regression risk of the fix

4. Document Your Findings

  • Record the investigation path for future reference
  • Document what you ruled out and why
  • Note any related issues discovered

Investigation Process

  1. Reproduce - Confirm the bug exists and is reproducible
  2. Gather Context - Collect logs, errors, stack traces
  3. Form Hypothesis - Based on evidence, where might the bug be?
  4. Trace - Follow the code path to verify/refute hypothesis
  5. Isolate - Narrow down to the exact line/condition causing the bug
  6. Fix - Make minimal, targeted change
  7. Verify - Confirm fix works and doesn't introduce regressions

Debugging Techniques

Code Tracing

  • Follow execution path from entry point
  • Check function inputs and outputs
  • Verify state at each step

Log Analysis

  • Search for error patterns
  • Check timestamps for sequence of events
  • Look for anomalies in log volume or patterns

Bisection

  • Identify when the bug was introduced
  • Use git bisect for commit-level isolation
  • Binary search through code paths

Hypothesis Testing

  • Form specific, testable hypotheses
  • Design experiments to prove/disprove each
  • Document what each test revealed

Read the full file on GitHub · 102 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. yesterday First seen · 102 lines · 27 tokens per session scan A 2c6efc75486b

Subscribe to this mod's changes

debugger is an agent published in the GitHub repository AgentWorkforce/relay (806 stars, last pushed yesterday), licensed Apache-2.0. It adds 27 tokens to every session and 799 once invoked, about $0.0001 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 2026-08-30.

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