Jij MCP Server

Instructions

Check the code for JijModeling rules.

Args:
    code (str): The code to check.

Returns:
    dict: The result of the check.

Implementation Reference

• jij_mcp/mcp_setting.py:99-110 (registration)

  Registration of the 'jm_check' MCP tool. Thin handler that invokes the core checker function from jm_checker.

  @mcp.tool()
  def jm_check(code: str) -> dict:
      """
      Check the code for JijModeling rules.
  
      Args:
          code (str): The code to check.
  
      Returns:
          dict: The result of the check.
      """
      return jijmodeling_check(code)

• jij_mcp/jm_checker.py:57-89 (handler)

  Core handler logic for jm_check: detects 'for' loops (forbidden in JijModeling), executes code in PythonREPL to catch errors, returns diagnostic dict.

  def jijmodeling_check(code_string: str) -> dict:
      """
      Pythonコード文字列をJijModelingのルールに従ってチェックする関数
  
      Args:
          code_string (str): 解析対象のPythonコード文字列
  
      Returns:
          dict: チェック結果を含む辞書
      """
      # for文の検出
      for_loop_detected = detect_for_loop(code_string)
      if for_loop_detected:
          return {
              "for_loop_detected": True,
              "message": _jm_for_statement_check,
          }
  
      # PythonREPLを使用してコードを実行し、エラーをキャッチ
      result = PythonREPL.run(code_string)
  
      if result["status"] == "error":
          return {
              "for_loop_detected": False,
              "message": _jm_for_statement_check,
              "error": result["error"],
          }
  
      return {
          "for_loop_detected": False,
          "message": "No for loop detected and no errors found.",
      }

• jij_mcp/jm_checker.py:91-119 (helper)

  Helper function to detect 'for' loops using AST parsing (primary) or regex (fallback).

  def detect_for_loop(code_string):
      """
      Pythonコード文字列からfor文の存在を検出する関数
  
      Args:
          code_string (str): 解析対象のPythonコード文字列
  
      Returns:
          bool: for文が存在する場合はTrue、存在しない場合はFalse
      """
      # 方法1: ASTを使用した解析（構文的に正しいコードの場合）
      try:
          tree = ast.parse(code_string)
          for node in ast.walk(tree):
              if isinstance(node, ast.For):
                  return True
      except SyntaxError:
          # 構文エラーがある場合は正規表現による検出に進む
          pass
  
      # 方法2: 正規表現を使用した解析（ASTが適用できない場合のバックアップ）
      # for文の正規表現パターン: 'for'の後にスペースまたはタブ、その後に変数名、'in'が続く形式
      pattern = r"\bfor\s+[a-zA-Z_][a-zA-Z0-9_]*\s+in\b"
  
      if re.search(pattern, code_string):
          return True
  
      return False

• jij_mcp/jm_checker.py:6-54 (helper)

  Helper string containing guidance and examples on avoiding Python 'for' loops in JijModeling using jm.Element and jm.sum.

  _jm_for_statement_check = """In JijModeling, you cannot use Python loops directly. Instead, you should use the Element objects.
  
  # How to write summation in JijModeling without Python loops.
  
  The wrong code:
  ```python
  objective = 0
  for l in range(n_l):
      for t in range(n_t):
          for p in range(n_p):
              for q in range(n_p):
                  if p != q:
                      objective += ChangeCost[p, q] * Switch[p, q, l, t]
  ```
  
  The correct code:
  ```
  l = jm.Element("l", belongs_to=range(0, n_l))
  t = jm.Element("t", belongs_to=range(0, n_t))
  p = jm.Element("p", belongs_to=range(0, n_p))
  q = jm.Element("q", belongs_to=range(0, n_p))
  objective = jm.sum([l, t, p, (q, p != q)], ChangeCost[p, q] * Switch[p, q, l, t])
  ```
  
  # How to write forall in JijModeling without Python loops.
  
  The wrong code:
  ```python
  for l in range(n_l):
      for t in range(n_t):
          problem += jm.Constraint(
              "SingleProductPerLine",
              jm.sum([X[p, l, t] for p in range(n_p)]) <= 1,
              forall=[]
          )
  ```
  
  The correct code:
  ```python
  l = jm.Element("l", belongs_to=range(0, n_l))
  t = jm.Element("t", belongs_to=range(0, n_t))
  p = jm.Element("p", belongs_to=range(0, n_p))
  problem += jm.Constraint(
      "SingleProductPerLine",
      jm.sum(p, X[p, l, t]) <= 1,
      forall=[l, t]
  )
  ```
  """

• jij_mcp/mcp_setting.py:100-110 (schema)

  Input schema: code (str). Output: dict with keys like 'for_loop_detected', 'message', optional 'error'.

  def jm_check(code: str) -> dict:
      """
      Check the code for JijModeling rules.
  
      Args:
          code (str): The code to check.
  
      Returns:
          dict: The result of the check.
      """
      return jijmodeling_check(code)