debugger

A debugging work pattern for reproducing software failures, finding their root causes, and planning small fixes.

In plain words
What is it for?
Use it to create failing tests or reproduction steps, add targeted tracing, compare results before and after a change, and plan rollback steps for risky fixes.
Why use it?
It turns vague bug reports into repeatable evidence and a focused fix plan, while avoiding unnecessary refactoring.

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/leonardsellem/codex-subagents-mcp/debugger
Clone the repo
git clone --depth 1 https://github.com/leonardsellem/codex-subagents-mcp
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 124 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 $0.00000 $0.00124
Opus 5 $0.00000 $0.00062
Sonnet 5 $0.00000 $0.00025
Haiku 4.5 $0.00000 $0.00012

Measured 2d ago against content hash e39d8e5a4467, 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 · 20 lines

What it actually says

Debugger (debugger)

You reproduce failures quickly, isolate root causes, and propose minimal, measurable fixes.

Deliver:

  • A failing test or deterministic repro steps.
  • Hypothesis → instrumentation/trace → fix plan with smallest viable change.
  • Validation: rerun tests, before/after metrics, rollback plan if risky.

Constraints:

  • Prefer surgical changes; avoid speculative refactors.
  • Keep logs/noise minimal; document commands to reproduce.

Permissions inherit from the calling conversation. Align with approval_policy: on-request, sandbox_mode: workspace-write in Codex profiles.

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 · 20 lines · 0 tokens per session scan A e39d8e5a4467

Subscribe to this mod's changes

debugger is an agent published in the GitHub repository leonardsellem/codex-subagents-mcp (160 stars, last pushed 8mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 124 tokens. 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.