SymPy Sandbox MCP

Instructions

Implementation Reference

• src/sym_mcp/server.py:66-118 (handler)

  The 'sympy' tool is registered using @mcp.tool and implemented by the 'sympy_tool' function. It validates code using an AST guard and then executes it in a worker pool.

  @mcp.tool(name="sympy")
  async def sympy_tool(code: str) -> str:
      """SymPy sandbox tool: execute Python/SymPy math code.
  
      Safety boundaries:
      - Only sympy/math imports and calls are allowed.
      - System calls, file I/O, network access, and dynamic execution are blocked.
  
      Input rules:
      - Single argument: code (str).
      - You must print() the final answer; otherwise out may be empty.
      - Use multiple print() lines for multiple outputs.
  
      Recommended workflow:
      1) Define symbols and assumptions.
      2) Derive/solve step by step.
      3) Simplify intermediate expressions (simplify/factor/expand).
      4) Print final results.
  
      Retry guidance:
      - E_AST_BLOCK: remove unsafe statements and keep pure math code only.
      - E_TIMEOUT: reduce problem size, split steps, simplify before solving.
      - E_MEMORY: reduce dimensions or avoid constructing huge objects at once.
      """
      guard = validate_code(code)
      if not guard.ok:
          parsed = parse_guard_message(guard.message, hint_level=settings.hint_level)
          return _build_error_response(parsed.code, parsed.line, parsed.err, parsed.hint)
  
      pool = await _get_pool()
      try:
          result = await pool.exec(code)
      except WorkerPoolError as exc:
          parsed = parse_pool_error(str(exc), hint_level=settings.hint_level)
          return _build_error_response(parsed.code, parsed.line, parsed.err, parsed.hint)
      except Exception as exc:
          LOGGER.exception("unexpected pool error")
          parsed = parse_internal_error(str(exc), hint_level=settings.hint_level)
          return _build_error_response(parsed.code, parsed.line, parsed.err, parsed.hint)
  
      if not result.get("ok", False):
          parsed = parse_pool_error("worker执行失败", hint_level=settings.hint_level)
          return _build_error_response(parsed.code, parsed.line, parsed.err, parsed.hint)
  
      if result.get("success", False):
          stdout = (result.get("stdout") or "").rstrip()
          out, _ = _truncate(stdout)
          return _json_compact({"out": out})
  
      tb_text = result.get("traceback", "") or ""
      parsed = parse_traceback(tb_text, hint_level=settings.hint_level)
      return _build_error_response(parsed.code, parsed.line, parsed.err, parsed.hint)