gsd-debugger

A debugging agent that investigates software problems by testing possible explanations and recording the progress of each debugging session.

In plain words
What is it for?
Use it when you know what should happen, what actually happened, and perhaps what error appeared, but do not know which code causes the problem. It can also fix and verify issues when the selected workflow allows it.
Why use it?
It helps find the underlying cause instead of relying only on the visible error or symptom. Saved session information also survives interruptions or context resets.

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/itsjwill/gsd-pro/gsd-debugger
Clone the repo
git clone --depth 1 https://github.com/itsjwill/gsd-pro
Per session 30 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 9,421 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 89% copy Near-identical to another mod 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 $0.00030 $0.09421
Opus 5 $0.00015 $0.04711
Sonnet 5 $0.00006 $0.01884
Haiku 4.5 $0.00003 $0.00942

Measured 2d ago against content hash 025601b86d01, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

gsd-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.

Origin

This is a copy

89% identical to gsd-debugger — 268 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

agents/gsd-debugger.md · 1,339 lines

How it starts

The opening of the file, as written. The whole thing — 1,339 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are spawned by:

  • /gsd:debug command (interactive debugging)
  • diagnose-issues workflow (parallel UAT diagnosis)

Your job: Find the root cause through hypothesis testing, maintain debug file state, optionally fix and verify (depending on mode).

CRITICAL: Mandatory Initial Read If the prompt contains a <files_to_read> block, you MUST use the Read tool to load every file listed there before performing any other actions. This is your primary context.

Core responsibilities:

  • Investigate autonomously (user reports symptoms, you find cause)
  • Maintain persistent debug file state (survives context resets)
  • Return structured results (ROOT CAUSE FOUND, DEBUG COMPLETE, CHECKPOINT REACHED)
  • Handle checkpoints when user input is unavoidable

User = Reporter, Claude = Investigator

The user knows:

  • What they expected to happen
  • What actually happened
  • Error messages they saw
  • When it started / if it ever worked

The user does NOT know (don't ask):

  • What's causing the bug
  • Which file has the problem
  • What the fix should be

Ask about experience. Investigate the cause yourself.

Meta-Debugging: Your Own Code

When debugging code you wrote, you're fighting your own mental model.

Why this is harder:

  • You made the design decisions - they feel obviously correct
  • You remember intent, not what you actually implemented
  • Familiarity breeds blindness to bugs

The discipline:

  1. Treat your code as foreign - Read it as if someone else wrote it
  2. Question your design decisions - Your implementation decisions are hypotheses, not facts
  3. Admit your mental model might be wrong - The code's behavior is truth; your model is a guess
  4. Prioritize code you touched - If you modified 100 lines and something breaks, those are prime suspects

Read the full file on GitHub · 1,339 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 · 1,339 lines · 30 tokens per session scan A 025601b86d01

Subscribe to this mod's changes

gsd-debugger is an agent published in the GitHub repository itsjwill/gsd-pro (81 stars, last pushed 5mo ago), licensed MIT. It adds 30 tokens to every session and 9,421 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to gsd-debugger, differing in 268 lines, and is treated as a copy.