LLDB MCP Server

Instructions

Register sets:
- 'general': General purpose registers (rax, rbx, rsp, etc.)
- 'float': Floating point registers
- 'vector': SIMD/vector registers (xmm, ymm)
- 'all': All register sets

Args:
    params: RegistersInput with breakpoint and register selection

Returns:
    str: Register values in hexadecimal format

Implementation Reference

• lldb_mcp_server.py:1010-1047 (handler)

  Main handler function that executes LLDB commands to read CPU registers at a specified breakpoint and returns formatted output.

  async def lldb_registers(params: RegistersInput) -> str:
      """View CPU register values at a breakpoint.
  
      Register sets:
      - 'general': General purpose registers (rax, rbx, rsp, etc.)
      - 'float': Floating point registers
      - 'vector': SIMD/vector registers (xmm, ymm)
      - 'all': All register sets
  
      Args:
          params: RegistersInput with breakpoint and register selection
  
      Returns:
          str: Register values in hexadecimal format
      """
      commands = [
          f"target create {params.executable}",
          f"breakpoint set --name {params.breakpoint}",
          "run" + (" " + " ".join(params.args) if params.args else ""),
      ]
  
      if params.specific_registers:
          reg_cmd = f"register read {' '.join(params.specific_registers)}"
      elif params.register_set == "all":
          reg_cmd = "register read --all"
      elif params.register_set == "float":
          reg_cmd = "register read --set 1"  # Usually FPU
      elif params.register_set == "vector":
          reg_cmd = "register read --set 2"  # Usually SSE/AVX
      else:
          reg_cmd = "register read"
  
      commands.append(reg_cmd)
      commands.append("quit")
  
      result = _run_lldb_script(commands)
  
      return f"## Registers at `{params.breakpoint}`\n\n```\n{result['output'].strip()}\n```"

• lldb_mcp_server.py:345-362 (schema)

  Pydantic input schema defining parameters for the lldb_registers tool, including executable path, breakpoint, register set, specific registers, and arguments.

  class RegistersInput(BaseModel):
      """Input for viewing registers."""
  
      model_config = ConfigDict(str_strip_whitespace=True)
  
      executable: str = Field(..., description="Path to the executable", min_length=1)
      breakpoint: str = Field(..., description="Breakpoint location to stop at", min_length=1)
      register_set: str = Field(
          default="general",
          description="Register set to display: 'general', 'float', 'vector', 'all'",
      )
      specific_registers: list[str] | None = Field(
          default=None, description="Specific register names to show (e.g., ['rax', 'rbx', 'rsp'])"
      )
      args: list[str] | None = Field(
          default=None, description="Command-line arguments to pass to the program"
      )

• lldb_mcp_server.py:1000-1009 (registration)

  MCP tool registration decorator that registers the lldb_registers handler with the FastMCP server, including metadata annotations.

  @mcp.tool(
      name="lldb_registers",
      annotations={
          "title": "View Registers",
          "readOnlyHint": True,
          "destructiveHint": False,
          "idempotentHint": True,
          "openWorldHint": False,
      },
  )