LLDB MCP Server

Instructions

Shows:
- Thread IDs and names
- Current execution point for each thread
- Stop reason (if stopped)
- Optionally: backtrace for each thread

Args:
    params: ThreadsInput with executable and optional core file

Returns:
    str: Thread listing with state information

Implementation Reference

• lldb_mcp_server.py:1163-1198 (handler)

  The main handler function that executes LLDB commands to examine threads in a target executable or core dump.

  async def lldb_threads(params: ThreadsInput) -> str:
      """List all threads and their current state.
  
      Shows:
      - Thread IDs and names
      - Current execution point for each thread
      - Stop reason (if stopped)
      - Optionally: backtrace for each thread
  
      Args:
          params: ThreadsInput with executable and optional core file
  
      Returns:
          str: Thread listing with state information
      """
      commands = []
  
      if params.core_file:
          commands.append(f"target create {params.executable} --core {params.core_file}")
      else:
          commands.append(f"target create {params.executable}")
          if params.breakpoint:
              commands.append(f"breakpoint set --name {params.breakpoint}")
              commands.append("run")
  
      commands.append("thread list")
  
      if params.show_backtrace:
          commands.append("thread backtrace all")
  
      if not params.core_file:
          commands.append("quit")
  
      result = _run_lldb_script(commands)
  
      return f"## Threads\n\n```\n{result['output'].strip()}\n```"

• lldb_mcp_server.py:417-425 (schema)

  Pydantic BaseModel defining the input parameters for the lldb_threads tool.

  class ThreadsInput(BaseModel):
      """Input for examining threads."""
  
      model_config = ConfigDict(str_strip_whitespace=True)
  
      executable: str = Field(..., description="Path to the executable", min_length=1)
      breakpoint: str | None = Field(default=None, description="Breakpoint location to stop at")
      core_file: str | None = Field(default=None, description="Path to core dump file")
      show_backtrace: bool = Field(default=False, description="Show backtrace for each thread")

• lldb_mcp_server.py:1153-1162 (registration)

  MCP decorator that registers the lldb_threads tool with the specified name and annotations.

  @mcp.tool(
      name="lldb_threads",
      annotations={
          "title": "Examine Threads",
          "readOnlyHint": True,
          "destructiveHint": False,
          "idempotentHint": True,
          "openWorldHint": False,
      },
  )