Lldb_mcp

What is Lldb_mcp?

Lldb_mcp is a simple MCP server for the LLDB debugger with minimal dependencies. It provides two commands (lldb_init and lldb) and works well with o4-mini and Gemini 2.5 Pro. Output is captured automatically, so no copy-paste is needed.

How to use Lldb_mcp?

Clone the repository, create a Python virtual environment, install fastmcp, then configure your MCP client with the path to the virtual environment’s Python and the lldb_mcp.py script. Additionally, import lldb_server.py into a running LLDB session. The server must be started manually inside an LLDB session.

Key features of Lldb_mcp

• Minimal dependencies (less than 200 lines of code)
• Only two commands: lldb_init and lldb
• Automatic output capture – no manual copy-paste
• Synchronous LLDB operation avoids complex event listeners
• Command chaining is disallowed for safety
• Returns “Executed successfully” when a command produces no output

Use cases of Lldb_mcp

• Debugging programs using LLMs that can issue LLDB commands
• Automating LLDB interactions via MCP protocol without manual terminal work
• Using o4-mini or Gemini 2.5 Pro to control LLDB debugging sessions
• Safe, manually‑started LLDB command execution with a blacklist of dangerous commands

FAQ from Lldb_mcp

How does Lldb_mcp handle command execution?

Lldb_mcp calls HandleCommand with SetAsync(False) to block and capture all output directly. This avoids complex event listeners and polling.

What are the runtime requirements for Lldb_mcp?

Python 3, the fastmcp library, and a running LLDB session. The server must be started manually inside an LLDB session.

Where does data live?

All LLDB commands are executed in the local LLDB session; no data is sent to external servers except what the MCP protocol exchanges with the client.

What are known limitations of Lldb_mcp?

Some commands may succeed without output (handled by returning “Executed successfully”). The “Continue” command can run indefinitely until a breakpoint is hit, causing the MCP to wait forever. o4-mini may hallucinate the --address flag in memory commands.

How does Lldb_mcp ensure safety?

The server must be started manually in a LLDB session. Certain commands are blacklisted (see lldb_server.py), and command chaining is not allowed.