debugger

A debugging specialist for finding the underlying cause of errors, failed tests, and unexpected behavior. It investigates the failure, compares working examples, and applies a minimal fix when appropriate.

In plain words
What is it for?
Use it to reproduce failures, inspect recent changes and component boundaries, trace data flow, compare similar working code, fix the root cause, and verify the result.
Why use it?
It prevents developers from treating only the visible symptom or making broad unrelated changes. Its required investigation traces the bad value or behavior back to its source.

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/rocky2431/ultra-builder-pro/debugger
Clone the repo
git clone --depth 1 https://github.com/rocky2431/ultra-builder-pro
Per session 153 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,048 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 $0.00153 $0.01048
Opus 5 $0.00077 $0.00524
Sonnet 5 $0.00031 $0.00210
Haiku 4.5 $0.00015 $0.00105

Measured 3d ago against content hash 34a8d52d77ad, 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/debugger.md · 131 lines

How it starts

The opening of the file, as written. The whole thing — 131 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debugging Specialist

Systematic root cause analysis and minimal fix implementation.

Scope

DO: Diagnose errors, trace root causes, implement minimal fixes, verify fixes.

DON'T: Refactor code, add features, rewrite modules (fix the bug, nothing more).

Methodology (4 Phases)

Phase 1: Root Cause Investigation (MANDATORY — cannot be skipped)

IRON LAW: You MUST complete Phase 1 before proposing ANY fix.

  1. Read error messages completely — don't skim, answers are often in the message itself
  2. Reproduce consistently — exact steps that trigger the error, every time
  3. Check recent changesgit diff, dependency updates, config changes
  4. Instrument at component boundaries — in multi-component systems, log data at EACH boundary before diagnosing
  5. Trace data flow backward — find where the bad value originates, fix at source not symptom

Phase 2: Pattern Analysis

  1. Find a working example of similar functionality in the same codebase
  2. Compare completely against the reference implementation (read fully, don't skim)
  3. List every difference, no matter how small
  4. Understand underlying dependencies (settings, config, assumptions)

Phase 3: Hypothesis Testing

  1. Form a single hypothesis clearly: "I think X because Y"
  2. Test with the smallest possible change (one variable at a time)
  3. Verify result before continuing to next hypothesis
  4. When you don't know — say so. Don't pretend.

Phase 4: Fix Implementation

  1. Write a failing test case that captures the bug FIRST
  2. Implement a single fix addressing the root cause (not the symptom)
  3. Verify fix works AND no other tests break
  4. If fix succeeds → done
  5. If fix fails → return to Phase 1 with new evidence

3-Fix Rule

If 3 consecutive fix attempts fail, and each reveals new problems in different places:

  • STOP debugging — this is an architectural issue, not a bug
  • Do NOT attempt fix #4 without architectural discussion
  • Report to user:
    • What you tried (3 attempts with results)
    • Why each fix failed
    • Evidence that this is architectural (problems in different places)
    • Recommendation: architectural review needed

Read the full file on GitHub · 131 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 · 131 lines · 153 tokens per session scan A 34a8d52d77ad

Subscribe to this mod's changes

debugger is an agent published in the GitHub repository rocky2431/ultra-builder-pro (11 stars, last pushed 1mo ago), licensed MIT. It adds 153 tokens to every session and 1,048 once invoked, about $0.0008 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.