DebugMCP (MCP server) — Use Cases, Install & Live Demo

Name: DebugMCP MCP Server
Author: microsoft

Why use it

Key features

14 debugger tools — start/stop, step over/into/out, breakpoints, evaluate
Line-content breakpoints (resilient to source edits)
9 languages supported via existing VS Code language extensions
100% local — no telemetry, no credentials needed
Auto-registers MCP server on extension activation

Live Demo

What it looks like in practice

debug-mcp-microsoft.replay ▶ ready

0/0

Install

Pick your client

~/Library/Application Support/Claude/claude_desktop_config.json · Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "debug-mcp-microsoft": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "http://localhost:3001/mcp"
      ]
    }
  }
}

Open Claude Desktop → Settings → Developer → Edit Config. Restart after saving.

~/.cursor/mcp.json · .cursor/mcp.json

{
  "mcpServers": {
    "debug-mcp-microsoft": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "http://localhost:3001/mcp"
      ]
    }
  }
}

Cursor uses the same mcpServers schema as Claude Desktop. Project config wins over global.

VS Code → Cline → MCP Servers → Edit

{
  "mcpServers": {
    "debug-mcp-microsoft": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "http://localhost:3001/mcp"
      ]
    }
  }
}

Click the MCP Servers icon in the Cline sidebar, then "Edit Configuration".

~/.codeium/windsurf/mcp_config.json

{
  "mcpServers": {
    "debug-mcp-microsoft": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "http://localhost:3001/mcp"
      ]
    }
  }
}

Same shape as Claude Desktop. Restart Windsurf to pick up changes.

~/.continue/config.json

{
  "mcpServers": [
    {
      "name": "debug-mcp-microsoft",
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "http://localhost:3001/mcp"
      ]
    }
  ]
}

Continue uses an array of server objects rather than a map.

~/.config/zed/settings.json

{
  "context_servers": {
    "debug-mcp-microsoft": {
      "command": {
        "path": "npx",
        "args": [
          "-y",
          "mcp-remote",
          "http://localhost:3001/mcp"
        ]
      }
    }
  }
}

Add to context_servers. Zed hot-reloads on save.

claude mcp add debug-mcp-microsoft -- npx -y mcp-remote http://localhost:3001/mcp

One-liner. Verify with claude mcp list. Remove with claude mcp remove.

Use Cases

Real-world ways to use DebugMCP

Have Claude step through a failing test instead of reading prints

👤 Backend / app devs ⏱ ~15 min beginner

When to use: A test fails with no clear stack — print debugging will take forever.

Prerequisites

DebugMCP installed in VS Code — Marketplace → ozzafar.debugmcpextension
Language debug extension (e.g., Python for .py) — Auto-prompted by VS Code on first run

Flow

Set up

Use debugmcp. Add a breakpoint on the line assert result == expected in tests/test_orders.py.✓ Copied

→ Breakpoint reported as set; line content matched
Run

Start debugging tests/test_orders.py with the failing test.✓ Copied

→ Session paused at breakpoint
Inspect

Show me all local variables. What's result actually contain?✓ Copied

→ Variable dump with concrete values
Step + diagnose

Step into the function that built result. Tell me where it diverged from expected.✓ Copied

→ Code-anchored root cause

Outcome: Bug located by stepping, not guessing — minutes instead of an hour.

Pitfalls

Breakpoint by line number drifts after edits — Use line content matching (DebugMCP supports this natively)

Combine with: filesystem

Pin down a heisenbug with conditional breakpoints

👤 Devs facing intermittent bugs ⏱ ~25 min intermediate

When to use: Bug only repros under specific input — you need to halt only on that case.

Flow

Conditional break

Add a breakpoint at the process(order) call that fires only when order.id starts with 'EXP-'.✓ Copied

→ Conditional breakpoint installed
Drive repro

Run the integration suite. When we stop, evaluate the order DTO and the request headers.✓ Copied

→ Exact failing input captured

Outcome: Heisenbug becomes a regular bug.

Pitfalls

Conditional eval slows the loop — Narrow the condition; keep it pure (no side effects)

Use the debugger as documentation for unfamiliar code

👤 New hires onboarding to a service ⏱ ~30 min beginner

When to use: You inherited a service and the data flow is opaque.

Flow

Trace entry

Set a breakpoint at the HTTP handler for /orders. Run a sample request and step through every call until response is returned. Narrate as you go.✓ Copied

→ Step-by-step trace with file:line annotations

Outcome: A behavioral map of the service that no diagram captured.

Pitfalls

Trace gets too deep — Use step_over for known-boring frames, step_into only the interesting ones

Combinations

Pair with other MCPs for X10 leverage

debug-mcp-microsoft + filesystem

Read source while stepping to decide next move

Step into the call. While paused, show me the surrounding function via filesystem.✓ Copied

debug-mcp-microsoft + github

Open a PR with the fix you just verified via the debugger

We confirmed the bug. Open a PR with the fix and reference the debug session in the description.✓ Copied

Tools

What this MCP exposes

Tool	Inputs	When to call	Cost
start_debugging	fileFullPath, workingDirectory, testName?, configurationName?	Begin a debug session	free
add_breakpoint	fileFullPath, lineContent	Mark a halt point by code content	free
step_over	(none)	Advance one source line	free
step_into	(none)	Descend into the called function	free
get_variables_values	scope: 'local'\|'global'\|'all'	Inspect state at the current pause point	free
evaluate_expression	expression: str	Test hypotheses without re-running	free
list_breakpoints	(none)	Audit current trap set	free

Cost & Limits

What this costs to run

API quota: Local — no quota
Tokens per call: 100–500 per debug action
Monetary: Free (MIT)
Tip: Stepping is cheaper than print-debug-loop iterations; trade tokens for faster diagnosis

Security

Permissions, secrets, blast radius

Minimum scopes: Local file read for source mapping

Credential storage: None — no creds needed

Data egress: None — fully local

Never grant: Network exposure of port 3001

Don't bind 0.0.0.0; keep it on localhost

Troubleshooting

Common errors and fixes

MCP server not detected after install

Restart VS Code; ensure extension is enabled and port 3001 is free

Verify: curl http://localhost:3001/mcp

Language not supported

Install the matching VS Code language debug extension first (e.g., ms-python.python for Python)

Verify: Run debug manually from VS Code UI to confirm

Breakpoint never hits

Source map mismatch — confirm you're debugging the same artifact you edited

Verify: Check launch.json `program` path

Alternatives

DebugMCP vs others

Alternative	When to use it instead	Tradeoff
Print / log statements	Quick one-off, no IDE attached	Cheap but slow to iterate; pollutes the codebase
Language-specific REPL	You want post-mortem inspection only	No live stepping; less rich than full debugger

More

Resources

📖 Read the official README on GitHub

🐙 Browse open issues

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