kernel-debug

A guide for attaching a debugger to a running Windows kernel, the core part of the operating system, through KDNET, a named pipe, or a serial connection.

In plain words
What is it for?
Use it to inspect processes, threads, modules, and I/O requests, set breakpoints, analyze blue-screen crashes, resume the target, and wait for it to stop again.
Why use it?
It helps investigate kernel crashes and driver failures while making the machine's paused or running state explicit, since breaking into a kernel stops the whole target.

Skill for Claude CodeCodex

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 skills/svnscha/mcp-windbg/kernel-debug
Any agent
npx skills add svnscha/mcp-windbg --skill kernel-debug
Clone the repo
git clone --depth 1 https://github.com/svnscha/mcp-windbg

Made for: Claude Code, Codex.

Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 543 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 $0.00043 $0.00543
Opus 5 $0.00022 $0.00271
Sonnet 5 $0.00009 $0.00109
Haiku 4.5 $0.00004 $0.00054

Measured 2d ago against content hash c25493b399a2, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

kernel-debug 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.

plugins/mcp-windbg/skills/kernel-debug/SKILL.md · 56 lines

What it actually says

Debug a live Windows kernel target

Drive a kernel target with the mcp-windbg kd tools. A kernel session halts the whole machine while it is broken in, so treat the target's running state as something you are responsible for.

Connecting

open_kd_session with the -k connection string:

  • KDNET: net:port=50000,key=1.2.3.4
  • Named pipe: com:pipe,port=\.\pipe\com_1,baud=115200,reconnect
  • Serial: com:port=COM1,baud=115200

Ask for the string rather than guessing it. The session arrives already broken in, so you can issue commands immediately.

Working the target

run_kd_command with the session_id. Common ground:

  • vertarget, !pcr, lm m nt to confirm what you are attached to
  • !process 0 0, !thread, !irp for OS state
  • bp <module>!<symbol> to set a breakpoint
  • !analyze -v after a bugcheck

Letting the machine run

This is where a kernel session differs from a dump, and where it is easy to leave a machine frozen:

  • g resumes the target and returns immediately. It does not wait, and it does not produce output until the target stops again.
  • wait_for_break blocks until the target stops on its own - a bugcheck, a breakpoint, a manual break - and returns what the debugger printed.
  • send_ctrl_break halts a running target now.
  • Any ordinary command issued while the target runs breaks in automatically first, and the reason it stopped leads that command's output.

A typical loop: set a breakpoint, g, tell the user to trigger the code path, then wait_for_break.

Finishing

close_kd_session with resume: true (the default) so the machine runs again. Only pass resume: false when the user explicitly wants it left halted, and say plainly that the machine will stay frozen until a debugger releases it.

If you set breakpoints, clear them with bc * before closing unless the user wants them kept.

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 · 56 lines · 43 tokens per session scan A c25493b399a2

Subscribe to this mod's changes

kernel-debug is a skill published in the GitHub repository svnscha/mcp-windbg (1,554 stars, last pushed 5d ago), licensed MIT. It adds 43 tokens to every session and 543 once invoked, about $0.0002 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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