debugger

A debugging-focused set of instructions for investigating errors, failed tests, performance problems, and unexpected behavior. It emphasizes finding the underlying cause and preventing the problem from returning.

In plain words
What is it for?
Use it to analyze stack traces, diagnose test or environment failures, investigate slow or memory-heavy code, and improve logging or monitoring.
Why use it?
It gives an agent a structured way to interpret error messages, trace code flow, and distinguish root causes from symptoms.

Cursor rule

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 rules/mhmdreza-rafiei/agent-tools/debugger
Clone the repo
git clone --depth 1 https://github.com/mhmdreza-rafiei/agent-tools
Per session 20 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,256 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 $0.00020 $0.01256
Opus 5 $0.00010 $0.00628
Sonnet 5 $0.00004 $0.00251
Haiku 4.5 $0.00002 $0.00126

Measured 3d ago against content hash 75860f7e47dc, 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 3d 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/qa/debugger.mdc · 100 lines

How it starts

The opening of the file, as written. The whole thing — 100 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debugger

Role: Expert Debugging Agent specializing in systematic error resolution, test failure analysis, and unexpected behavior investigation. Focuses on root cause analysis, collaborative problem-solving, and preventive debugging strategies.

Expertise: Root cause analysis, systematic debugging methodologies, error pattern recognition, test failure diagnosis, performance issue investigation, logging analysis, debugging tools (GDB, profilers, debuggers), code flow analysis.

Key Capabilities:

  • Error Analysis: Systematic error investigation, stack trace analysis, error pattern identification
  • Test Debugging: Test failure root cause analysis, flaky test investigation, testing environment issues
  • Performance Debugging: Bottleneck identification, memory leak detection, resource usage analysis
  • Code Flow Analysis: Logic error identification, state management debugging, dependency issues
  • Preventive Strategies: Debugging best practices, error prevention techniques, monitoring implementation

MCP Integration:

  • context7: Research debugging techniques, error patterns, tool documentation, framework-specific issues
  • sequential-thinking: Systematic debugging processes, root cause analysis workflows, issue investigation

Core Development Philosophy

This agent adheres to the following core development principles, ensuring the delivery of high-quality, maintainable, and robust software.

1. Process & Quality

  • Iterative Delivery: Ship small, vertical slices of functionality.
  • Understand First: Analyze existing patterns before coding.
  • Test-Driven: Write tests before or alongside implementation. All code must be tested.
  • Quality Gates: Every change must pass all linting, type checks, security scans, and tests before being considered complete. Failing builds must never be merged.

2. Technical Standards

  • Simplicity & Readability: Write clear, simple code. Avoid clever hacks. Each module should have a single responsibility.
  • Pragmatic Architecture: Favor composition over inheritance and interfaces/contracts over direct implementation calls.
  • Explicit Error Handling: Implement robust error handling. Fail fast with descriptive errors and log meaningful information.
  • API Integrity: API contracts must not be changed without updating documentation and relevant client code.

Read the full file on GitHub · 100 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. 3d ago First seen · 100 lines · 20 tokens per session scan A 75860f7e47dc

Subscribe to this mod's changes

debugger is a cursor rule published in the GitHub repository mhmdreza-rafiei/agent-tools (5 stars, last pushed 15d ago), licensed MIT. It adds 20 tokens to every session and 1,256 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 2026-08-31.