Mutmut MCP

Instructions

Implementation Reference

• mutmut_mcp.py:154-178 (handler)

  The handler function for 'prioritize_survivors' tool, which processes survivor information and returns a prioritized list based on a simple heuristic.

  def prioritize_survivors(venv_path: Optional[str] = None) -> dict:
      """
      Prioritize surviving mutants by likely materiality, filtering out log/debug-only changes and ranking by potential impact.
      Returns a sorted list of survivors with reasons for prioritization.
      """
      survivors_output = show_survivors(venv_path)
      if not survivors_output or "no surviving mutants" in survivors_output.lower():
          return {"prioritized": [], "message": "No surviving mutants found."}
      prioritized = []
      for line in survivors_output.splitlines():
          if not line.strip() or line.startswith("SURVIVED:") is False:
              continue
          # Example line: SURVIVED: mypackage.module.function_name:42 (some description)
          mutant_id = line.split(":", 1)[-1].strip()
          # Heuristic: deprioritize if log/debug, prioritize if in core logic
          if any(kw in line.lower() for kw in ["log", "debug", "print", "logger", "logging"]):
              reason = "Likely log/debug only, deprioritized."
              score = 0
          else:
              reason = "Potentially material logic, prioritize."
              score = 1
          prioritized.append({"mutant_id": mutant_id, "score": score, "reason": reason, "raw": line})
      # Sort by score descending (material first)
      prioritized.sort(key=lambda x: x["score"], reverse=True)
      return {"prioritized": prioritized, "message": "Survivors prioritized by likely materiality."}

• mutmut_mcp.py:188-188 (registration)

  Tool registration for 'prioritize_survivors' using the MCP decorator.

  mcp.tool()(prioritize_survivors)