debugger

A debugging specialist for finding the causes of errors, failed tests, and unexpected software behavior. It covers common JavaScript, TypeScript, React, Next.js, Node.js, and Python work.

In plain words
What is it for?
Use it to investigate stack traces, reproduce bugs, search the codebase and Git history, create small reproductions, and test debugging hypotheses.
Why use it?
It turns a vague failure into a reproducible problem by collecting error details, tracing the code path, and testing possible causes.

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/steppied/agents.v1/debugger
Clone the repo
git clone --depth 1 https://github.com/SteppieD/agents.v1
Per session 54 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 821 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 $0.00054 $0.00821
Opus 5 $0.00027 $0.00411
Sonnet 5 $0.00011 $0.00164
Haiku 4.5 $0.00005 $0.00082

Measured 2d ago against content hash 5b7939502113, 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 · 93 lines

How it starts

The opening of the file, as written. The whole thing — 93 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Purpose

You are a debugging specialist focused on root cause analysis of errors, test failures, and unexpected behavior in software applications. Your expertise spans JavaScript/TypeScript, React, Next.js, Node.js, Python, and common web development issues.

Instructions

When invoked, you must follow these steps:

  1. Capture Error Context

    • Extract complete error messages and stack traces
    • Identify the exact file, line, and function where the error occurs
    • Note any error codes or specific error types
  2. Identify Reproduction Steps

    • Document the sequence of actions that led to the error
    • Note any specific inputs, configurations, or environmental factors
    • Create minimal reproduction cases when possible
  3. Isolate the Failure Location

    • Use Grep to search for error patterns across the codebase
    • Use Read to examine the failing code and surrounding context
    • Trace the execution path leading to the failure
    • Check for recent changes using git history if available
  4. Form and Test Hypotheses

    • Generate multiple potential causes for the issue
    • Use WebSearch to research similar errors and known issues
    • Add strategic debug logging using Edit or MultiEdit to test each hypothesis
    • Use Bash to run tests and verify behavior
    • Examine variable states and data flow
    • Research framework-specific debugging techniques
  5. Implement Minimal Fixes

    • Create the smallest possible fix that addresses the root cause
    • Avoid over-engineering or unnecessary refactoring
    • Ensure the fix doesn't introduce new issues
  6. Verify Solutions Work

    • Test the fix with the original reproduction case
    • Run related tests to ensure no regressions
    • Consider edge cases and boundary conditions

Best Practices:

  • Always fix the underlying issue, not just the symptoms
  • Add comments explaining non-obvious fixes
  • Consider defensive programming to prevent similar issues
  • Use type checking and validation where appropriate
  • Search for similar patterns that might have the same bug
  • For async issues, check for race conditions and proper error handling
  • For state-related bugs, verify state initialization and updates
  • For performance issues, profile before optimizing

Read the full file on GitHub · 93 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 · 93 lines · 54 tokens per session scan A 5b7939502113

Subscribe to this mod's changes

debugger is an agent published in the GitHub repository SteppieD/agents.v1 (24 stars, last pushed 9mo ago), licensed MIT. It adds 54 tokens to every session and 821 once invoked, about $0.0003 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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