Overview

LLDB MCP Server connects the LLDB debugger to a Model Context Protocol (MCP) host so an LLM agent (for example, Anthropic Claude configured with MCP) can start and control live LLDB debugging sessions. The server exposes a set of RPC-style commands that let the model manage sessions, load binaries or core dumps, set breakpoints, step through code, inspect memory/registers, and run arbitrary LLDB commands — enabling AI-assisted, reproducible debugging workflows.

This is particularly useful for reproducing and iterating on hard-to-find issues like buffer overflows: the agent can run the target program, catch a crash, capture backtraces and memory dumps, and propose concrete fixes — while the server preserves logs and session state so every step is repeatable and auditable.

Features

Manage multiple concurrent LLDB sessions (start, list, terminate).
Load executables, attach to running processes, or open core dumps.
Set and list breakpoints and watchpoints.
Fine-grained execution control: run, continue, step, next, finish, kill.
Inspect process state: memory, registers, stack frames, threads, disassembly.
Execute arbitrary LLDB commands and evaluate expressions in the current frame.
Output traces and debug logs for reproducibility.
Optional debug mode for verbose server-side logging.

Installation / Configuration

Clone the repository and install the MCP dependency:

git clone https://github.com/stass/lldb-mcp.git
cd lldb-mcp
pip install mcp

Start the MCP server (example):

python3 lldb_mcp.py --host 127.0.0.1 --port 6000
# add --debug for verbose logs

Configure your MCP client (e.g., Claude desktop) to use the server. Example JSON entry for the MCP configuration:

"mcpServers": {
  "lldb-mcp": {
    "command": "python3",
    "args": ["/path/to/lldb-mcp/lldb_mcp.py", "--host", "127.0.0.1", "--port", "6000"],
    "disabled": false
  }
}

Requirements:

Python 3.7+
LLDB installed and reachable on the PATH
MCP-capable client (e.g., Claude desktop with MCP support)

Available Tools / Resources

The server exposes discrete commands (useful when driving LLDB from an LLM):

Category	Example Commands
Session management	lldb_start, lldb_terminate, lldb_list_sessions
Program loading	lldb_load, lldb_attach, lldb_load_core
Execution control	lldb_run, lldb_continue, lldb_step, lldb_next, lldb_finish, lldb_kill
Breakpoints / watchpoints	lldb_set_breakpoint, lldb_breakpoint_list, lldb_breakpoint_delete, lldb_watchpoint
Inspection	lldb_backtrace, lldb_print, lldb_examine, lldb_info_registers, lldb_frame_info, lldb_disassemble
Threads	lldb_thread_list, lldb_thread_select
Misc	lldb_command, lldb_expression, lldb_help

Use lldb_command to run any LLDB command text that doesn’t have a dedicated wrapper.

Use Cases

Reproducing and fixing a buffer overflow
- Compile the example that demonstrates overflow:
```
cc example/overflow.c -o a.out
```
- Ask the MCP-enabled assistant: “Start a session, run a.out with argument ‘hello’, and debug the crash.”
- The server will run the program under LLDB, capture the crash, produce a backtrace, dump relevant memory regions, and list suspicious stack frames and register values. The assistant can then suggest a fix (e.g., correcting a strncpy/memcpy size) and re-run the binary to verify the fix.
Post-mortem analysis using core dumps
- Load a core file with lldb_load_core to inspect the state at crash time without running the program.
Attaching to a live process for intermittent bugs
- Use lldb_attach to attach to a PID, set conditional breakpoints, and collect traces only when the condition triggers.
Teaching/debugging sessions
- Developers can use the server to produce reproducible transcripts of interactive debugging sessions for onboarding or bug reports.

Practical tips

When a command needs syntax not covered by the API, use lldb_command to send raw LLDB commands.
Use –debug on the server to capture full logs that can be attached to bug reports.
Each session has an ID; include the session ID when issuing follow-up commands so operations target the correct session.
If LLDB appears to hang or time out, confirm LLDB is installed and the server has permissions to debug/attach.

Repository and examples, including the overflow demo, are available at: https://github.com/stass/lldb-mcp.

LLDB MCP Server Automated Buffer Overflow Debugging