debug-mcp.net

MCP server for .NET debugging — enable AI agents to debug .NET applications interactively.

What is debug-mcp?

debug-mcp is a Model Context Protocol server that exposes .NET debugging capabilities as structured API tools. It allows AI assistants like Claude, GPT, or Copilot to:

• Launch or attach to .NET processes
• Set breakpoints, exception breakpoints, and tracepoints
• Step through code line by line
• Inspect variables, evaluate expressions, and read memory
• Analyze stack traces and threads
• Get full exception context with one call (exception autopsy)
• Navigate code with go-to-definition, find usages, and diagnostics
• Automatically resolve symbols from public symbol servers

Unlike similar tools that use external debuggers via DAP protocol, debug-mcp interfaces directly with the .NET runtime using ICorDebug APIs — the same approach used by JetBrains Rider.

Quick Start

Run

# No installation needed (.NET 10+)
dnx -y debug-mcp

Requirements

• .NET 10 SDK or later
• Linux (Windows and macOS support planned)

Configure with Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "dotnet-debugger": {
      "command": "dnx",
      "args": ["-y", "debug-mcp"]
    }
  }
}

Configure with Claude Code

Add to your .mcp.json:

{
  "mcpServers": {
    "dotnet-debugger": {
      "command": "dnx",
      "args": ["-y", "debug-mcp"]
    }
  }
}

Example Conversation

You: Debug my ASP.NET app and find why GetUser returns null

Claude: I'll launch your application and investigate.
        [Calls debug_launch with program path]
        [Calls breakpoint_set at UserService.cs:42]
        [Calls debug_continue]
        [Calls breakpoint_wait with 30s timeout]

        The breakpoint was hit. Let me check the variables.
        [Calls variables_get for current frame]

        I found the issue: the `userId` parameter is an empty string.
        The bug is in the calling code at line 28 where...

You: My app throws NullReferenceException somewhere in checkout. Find it.

Claude: I'll set an exception breakpoint and trigger the flow.
        [Calls debug_launch with program path]
        [Calls breakpoint_set_exception for System.NullReferenceException]
        [Calls debug_continue]
        [Calls breakpoint_wait with include_autopsy: true]

        Caught it! The exception was thrown in OrderService.cs at line 87.
        Here's the full context from the autopsy:
        - cart.Items was null because LoadCart() returned an empty cart
        - The null check at line 85 only checked cart, not cart.Items

Tools (34)

Category	Tools	Description
Session	debug_launch, debug_attach, debug_disconnect, debug_state	Start, stop, and monitor debug sessions
Execution	debug_continue, debug_pause, debug_step	Control program flow
Breakpoints	breakpoint_set, breakpoint_remove, breakpoint_list, breakpoint_enable, breakpoint_wait	Set and manage source breakpoints
Exception Breakpoints	breakpoint_set_exception	Break on specific exception types (first/second chance)
Tracepoints	tracepoint_set	Non-blocking breakpoints that log messages without pausing
Exception Autopsy	exception_get_context	Full exception analysis: type, message, inner exceptions, stack frames with source, and local variables
Inspection	threads_list, stacktrace_get, variables_get, evaluate	Examine program state
Memory	object_inspect, memory_read, layout_get, references_get, members_get	Deep object and memory analysis
Modules	modules_list, modules_search, types_get	Explore loaded assemblies and types
Code Analysis	code_load, code_goto_definition, code_find_usages, code_find_assignments, code_get_diagnostics	Roslyn-powered code navigation and diagnostics
Process I/O	process_write_input, process_read_output	Interact with debuggee stdin/stdout

Resources (4)

URI	Description
debugger://session	Current debug session state
debugger://breakpoints	All active breakpoints
debugger://threads	Thread list with states
debugger://source/{file}	Source file contents

Documentation

• Architecture — System design and components
• How Debugging Works — ICorDebug internals explained
• MCP Tools Reference — Complete API documentation
• MCP Resources — Subscribable state views
• Development Guide — Building, testing, contributing

Similar Projects

Project	Language	Approach	.NET Support
mcp-debugger	TypeScript	DAP	Via external debugger
dap-mcp	Python	DAP	Via external debugger
LLDB MCP	C++	Native	No
debug-mcp	C#	ICorDebug	Native, direct

License

AGPL-3.0 — see LICENSE for details.