set_vm_resources

Instructions

Implementation Reference

• src/mcp_utm/server.py:106-120 (registration)

  The @mcp.tool() decorator registers 'set_vm_resources' as an MCP tool. The function delegates to applescript.set_vm_resources and returns the config as dict.

  @mcp.tool()
  def set_vm_resources(
      name: str,
      memory: int | None = None,
      cpu_cores: int | None = None,
  ) -> dict:
      """Update memory and CPU cores of a stopped VM.
  
      Args:
          name: VM name (must be stopped)
          memory: Memory in MiB, or None to keep current
          cpu_cores: Number of CPU cores, or None to keep current
      """
      config = utm.set_vm_resources(name, memory=memory, cpu_cores=cpu_cores)
      return config.to_dict()

• src/mcp_utm/applescript.py:445-472 (handler)

  Core implementation: validates name, validates memory (64–1048576 MiB) and cpu_cores (1–256), builds AppleScript to update the VM configuration via UTM's scripting API, and returns a VMConfig dataclass.

  def set_vm_resources(name: str, memory: int | None = None, cpu_cores: int | None = None) -> VMConfig:
      """Update memory and/or CPU cores of a stopped VM."""
      _validate_vm_name(name)
      parts = []
      if memory is not None:
          memory = int(memory)
          if memory < 64 or memory > _MAX_MEMORY_MIB:
              raise ValueError(f"Memory must be 64–{_MAX_MEMORY_MIB} MiB, got {memory}")
          parts.append(f"set memory of conf to {memory}")
      if cpu_cores is not None:
          cpu_cores = int(cpu_cores)
          if cpu_cores < 1 or cpu_cores > _MAX_CPU_CORES:
              raise ValueError(f"CPU cores must be 1–{_MAX_CPU_CORES}, got {cpu_cores}")
          parts.append(f"set cpu cores of conf to {cpu_cores}")
      if not parts:
          return get_vm_config(name)
  
      updates = "\n            ".join(parts)
      script = f'''
      tell application "UTM"
          set vm to virtual machine named "{_esc(name)}"
          set conf to configuration of vm
          {updates}
          update configuration of vm with conf
      end tell
      '''
      _run(script)
      return get_vm_config(name)

• src/mcp_utm/applescript.py:107-123 (schema)

  VMConfig dataclass defines the output shape (name, memory, cpu_cores, mac_address, network_mode) returned by set_vm_resources.

  @dataclass
  class VMConfig:
      name: str
      memory: int  # MiB
      cpu_cores: int
      mac_address: str
      network_mode: str
  
      def to_dict(self) -> dict:
          return {
              "name": self.name,
              "memory": self.memory,
              "cpu_cores": self.cpu_cores,
              "mac_address": self.mac_address,
              "network_mode": self.network_mode,
          }

• src/mcp_utm/applescript.py:24-25 (helper)

  Validation constants used by set_vm_resources: _MAX_MEMORY_MIB (1048576) and _MAX_CPU_CORES (256).

  _MAX_MEMORY_MIB = 1048576  # 1 TiB
  _MAX_CPU_CORES = 256

• src/mcp_utm/applescript.py:33-36 (helper)

  Name validation helper called at the start of set_vm_resources.

  def _validate_vm_name(name: str) -> str:
      if not name or not _VM_NAME_RE.match(name):
          raise ValueError(f"Invalid VM name: {name!r} — only word characters, spaces, hyphens, and dots allowed")
      return name