Qwen DAP MCP — C/C++ Debugger for Claude Code, Codex & Qwen

Qwen DAP MCP — Native Debugger MCP for Claude Code, Codex, Qwen and AI Coding Agents

Debug native C/C++ crashes, hangs, deadlocks, Windows minidumps and core dumps with Claude Code, OpenAI Codex CLI, Qwen Code, Gemini CLI and other local MCP-compatible coding agents. Connect a real GDB, LLDB or CodeLLDB debugger through the Debug Adapter Protocol (DAP) and Model Context Protocol (MCP).

qwen-dap-mcp is a local Debug Adapter Protocol (DAP) → Model Context Protocol (MCP) bridge for native crash debugging, hang/deadlock triage, crash dumps, differential runtime analysis, remote targets, and bounded fix/verify workflows.

Originally designed for Qwen Code, but usable from other local stdio MCP clients including Claude Code and Codex CLI. The AI model may run in the cloud; the debugger bridge and target binary still run where the MCP process is started.

[Quick start](#quick-start) · [Capabilities](#what-it-does) · [Debugger support](#debugger-support) · [Safety](#safety-by-design) · [Docs](https://github.com/spk-c/Qwen-dap-mcp/blob/main/docs/README.md) · [Contributing](https://github.com/spk-c/Qwen-dap-mcp/blob/main/CONTRIBUTING.md)

Maintained Apache-2.0 fork of the original project by SLP-DEV1. The maintained source is spk-c/Qwen-dap-mcp; npm distributes @slp-dev1/qwen-dap-mcp. GitHub's main may be ahead of the latest published npm version. See fork notes and TypeScript migration status.

See it in action: C++ crash → evidence → verification

*Illustrated architecture/workflow, not a captured AI session or fabricated debugger transcript.* Reproduce an actual intentional crash in the project's own C++ fixture, collect a GDB backtrace, apply an illustrative change only in a temporary copy, and rerun the same command:

bash scripts/demo-native-crash.sh

Requires Linux, g++ and gdb. CI also executes the demo with a real debugger. [View step-by-step verified demo and Claude/Codex MCP setup](https://github.com/spk-c/Qwen-dap-mcp/blob/main/docs/demo-native-crash.md).

Why this exists

Coding agents can read source and propose patches, but native failures often cannot be diagnosed reliably from source alone. The useful evidence lives at runtime: thread stacks, registers, locals, disassembly, exception state, modules, memory, wait states, symbols, and crash dumps.

qwen-dap-mcp makes that evidence available through MCP and adds agent-oriented workflows on top of raw debugger primitives:

• Evidence first — inspect the actual failing process instead of guessing from source.
• High-level workflows — crash, hang, differential, causal tracing, progress probing, runtime-report, dump, and verification tools are designed for agents rather than humans driving a debugger console.
• Bounded automation — autonomous fix/verify state is explicit, serializable, iteration-limited, and re-checks the original reproduction.
• Small default surface — 18 core agent tools stay visible by default; forensic workflows and raw DAP controls are separate opt-in tiers.
• Local by default — the MCP server communicates over stdio and debugger adapters run locally unless you explicitly configure a validated remote target.

Quick start

Qwen Code

Install the current published npm version:

qwen extensions install @slp-dev1/qwen-dap-mcp

Or install the newest code directly from the maintained GitHub repository (this can be ahead of npm):

qwen extensions install spk-c/Qwen-dap-mcp

In Qwen Code, run /mcp and /skills to check that the qwen-dap-mcp server and the native-runtime-debug skill were discovered.

Prerequisites: Node.js 20+, and a supported native DAP debugger installed separately (CodeLLDB, LLVM lldb-dap, or GNU GDB DAP). This package is a bridge, not a bundled debugger. See platform setup.

Claude Code

Use a local Claude Code CLI with Node.js 20+ and an installed native DAP debugger:

claude mcp add --transport stdio --scope user qwen-dap-mcp -- npx -y @slp-dev1/qwen-dap-mcp

claude mcp list

See Claude Code native debugging guide for a setup check, test prompt, Windows notes and safety boundaries.

OpenAI Codex CLI

codex mcp add qwen-dap-mcp -- npx -y @slp-dev1/qwen-dap-mcp

codex mcp list

See Codex CLI + IDE debugging guide and versioned Codex TOML configuration.

Gemini CLI, Cursor, VS Code Copilot and other clients

Use a local stdio MCP entry pointing to npx -y @slp-dev1/qwen-dap-mcp. These clients have different configuration schemas: Gemini CLI and Cursor use mcpServers, while VS Code's .vscode/mcp.json uses servers. See multi-client setup and compatibility matrix and the tested configuration examples.

Cloud execution boundary: Claude Code or Codex CLI may call a cloud AI model while the CLI and debugger remain on your desktop. A browser-only Claude.ai/ChatGPT session or a remote Codex task cannot automatically access your PC's local stdio MCP server or Windows processes. Remote debugging requires separately authorized local execution or a protected connection; never expose a raw debugger port to the public internet.

Other stdio MCP clients

Run the published package with npx:

npx -y @slp-dev1/qwen-dap-mcp --help

npx -y @slp-dev1/qwen-dap-mcp --version

Configure a trusted local MCP client with:

{

"mcpServers": { "qwen-dap-mcp": { "command": "npx", "args": ["-y", "@slp-dev1/qwen-dap-mcp"] } } }

When started without --help or --version, the CLI operates as a local stdio MCP server. Client configuration syntax may vary.

Update an existing installation

Update the npm-backed Qwen extension using the extension manager in your installed Qwen Code version, or reinstall the package with the command above. For npx, restart the MCP client to use newly resolved versions. npm releases are immutable: README changes appear on npmjs.com only after publishing a new package version, not when GitHub's README changes.

MCP client compatibility

The project includes automatic protocol-level stdio initialize + tools/list smoke tests with Claude Code, Codex CLI and Gemini client identities. These prove the shared MCP server protocol and example configuration consistency, not full end-to-end verification inside proprietary client applications. Native debugger E2E checks run separately. Run npm run test:clients from a built checkout.

30-second example

You: Debug why app.exe crashes with --repro

Coding agent ↓ qwen-dap-mcp starts a DAP debugger ↓ captures the native failure + project-controlled frame ↓ correlates stack + registers + locals + disassembly ↓ backtracks runtime evidence toward the likely producer ↓ agent applies a minimal source fix ↓ builds and repeats the original reproduction ↓ verifies whether the original crash fingerprint is gone

The MCP server supplies debugger evidence and bounded workflow state. Source editing, builds, tests, and source-control operations stay with the coding agent's normal authorized tools.

What it does

Tool surfaces

The default agent toolset intentionally exposes 18 core tools so coding models spend less context and selection effort on rarely needed forensic workflows.