MCP Python Interpreter

Instructions

List installed packages for a specific Python environment.

Args:
    environment: Name of the Python environment

Implementation Reference

• mcp_python_interpreter/server.py:484-510 (handler)

  The handler function decorated with @mcp.tool(), which implements the core logic of listing installed packages in the specified Python environment by calling helper functions to get environments and packages.

  @mcp.tool()
  def list_installed_packages(environment: str = "default") -> str:
      """
      List installed packages for a specific Python environment.
      
      Args:
          environment: Name of the Python environment
      """
      environments = get_python_environments()
      
      if environment == "default" and not any(e["name"] == "default" for e in environments):
          environment = "system"
      
      env = next((e for e in environments if e["name"] == environment), None)
      if not env:
          return f"Environment '{environment}' not found. Available: {', '.join(e['name'] for e in environments)}"
      
      packages = get_installed_packages(env["path"])
      
      if not packages:
          return f"No packages found in environment '{environment}'."
      
      result = f"Installed Packages in '{environment}':\n\n"
      for pkg in packages:
          result += f"- {pkg['name']} {pkg['version']}\n"
      
      return result

• mcp_python_interpreter/server.py:308-376 (helper)

  Helper function that discovers available Python environments (system, default, conda) by running subprocess commands to detect paths and versions.

  def get_python_environments() -> List[Dict[str, str]]:
      """Get all available Python environments."""
      environments = []
      
      if DEFAULT_PYTHON_PATH != sys.executable:
          try:
              result = subprocess.run(
                  [DEFAULT_PYTHON_PATH, "-c", "import sys; print(f'{sys.version_info.major}.{sys.version_info.minor}.{sys.version_info.micro}')"],
                  capture_output=True, text=True, check=True, timeout=10,
                  stdin=subprocess.DEVNULL,
                  creationflags=subprocess.CREATE_NO_WINDOW if sys.platform == "win32" else 0
              )
              version = result.stdout.strip()
              
              environments.append({
                  "name": "default",
                  "path": DEFAULT_PYTHON_PATH,
                  "version": version
              })
          except Exception as e:
              print(f"Error getting version for custom Python path: {e}", file=sys.stderr)
      
      environments.append({
          "name": "system",
          "path": sys.executable,
          "version": f"{sys.version_info.major}.{sys.version_info.minor}.{sys.version_info.micro}"
      })
      
      # Try conda environments
      try:
          result = subprocess.run(
              ["conda", "info", "--envs", "--json"],
              capture_output=True, text=True, check=False, timeout=10,
              stdin=subprocess.DEVNULL,
              creationflags=subprocess.CREATE_NO_WINDOW if sys.platform == "win32" else 0
          )
          
          if result.returncode == 0:
              conda_info = json.loads(result.stdout)
              for env in conda_info.get("envs", []):
                  env_name = os.path.basename(env)
                  if env_name == "base":
                      env_name = "conda-base"
                  
                  python_path = os.path.join(env, "bin", "python")
                  if not os.path.exists(python_path):
                      python_path = os.path.join(env, "python.exe")
                  
                  if os.path.exists(python_path):
                      try:
                          version_result = subprocess.run(
                              [python_path, "-c", "import sys; print(f'{sys.version_info.major}.{sys.version_info.minor}.{sys.version_info.micro}')"],
                              capture_output=True, text=True, check=True, timeout=10,
                              stdin=subprocess.DEVNULL,
                              creationflags=subprocess.CREATE_NO_WINDOW if sys.platform == "win32" else 0
                          )
                          version = version_result.stdout.strip()
                          
                          environments.append({
                              "name": env_name,
                              "path": python_path,
                              "version": version
                          })
                      except Exception:
                          pass
      except Exception as e:
          print(f"Error getting conda environments: {e}", file=sys.stderr)
      
      return environments

• mcp_python_interpreter/server.py:379-392 (helper)

  Helper function that executes 'pip list --format=json' via subprocess in the specified Python path to retrieve the list of installed packages as JSON.

  def get_installed_packages(python_path: str) -> List[Dict[str, str]]:
      """Get installed packages for a specific Python environment."""
      try:
          result = subprocess.run(
              [python_path, "-m", "pip", "list", "--format=json"],
              capture_output=True, text=True, check=True, timeout=30,
              stdin=subprocess.DEVNULL,
              creationflags=subprocess.CREATE_NO_WINDOW if sys.platform == "win32" else 0
          )
          return json.loads(result.stdout)
      except Exception as e:
          print(f"Error getting installed packages: {e}", file=sys.stderr)
          return []

• mcp_python_interpreter/server.py:484-484 (registration)

  The @mcp.tool() decorator registers the list_installed_packages function as an MCP tool.

  @mcp.tool()

• mcp_python_interpreter/server.py:485-491 (schema)

  Function signature and docstring providing input schema (environment parameter) and description for the tool.

  def list_installed_packages(environment: str = "default") -> str:
      """
      List installed packages for a specific Python environment.
      
      Args:
          environment: Name of the Python environment
      """