init() — langchain Function Reference

Architecture documentation for the __init__() function in tool_call_limit.py from the langchain codebase.

Function python LangChainCore MessageInterface

Entity Profile

LangChainCore→ MessageInterface→ __init__() — langchain Function Reference

Dependency Diagram

graph TD
  334dcb67_a99d_7d1b_fe5a_d24003d136d6["__init__()"]
  68f7858b_b207_3223_e360_e5e5b35adf21["ToolCallLimitMiddleware"]
  334dcb67_a99d_7d1b_fe5a_d24003d136d6 -->|defined in| 68f7858b_b207_3223_e360_e5e5b35adf21
  style 334dcb67_a99d_7d1b_fe5a_d24003d136d6 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/langchain_v1/langchain/agents/middleware/tool_call_limit.py lines 201–253

    def __init__(
        self,
        *,
        tool_name: str | None = None,
        thread_limit: int | None = None,
        run_limit: int | None = None,
        exit_behavior: ExitBehavior = "continue",
    ) -> None:
        """Initialize the tool call limit middleware.

        Args:
            tool_name: Name of the specific tool to limit. If `None`, limits apply
                to all tools.
            thread_limit: Maximum number of tool calls allowed per thread.
                `None` means no limit.
            run_limit: Maximum number of tool calls allowed per run.
                `None` means no limit.
            exit_behavior: How to handle when limits are exceeded.

                - `'continue'`: Block exceeded tools with error messages, let other
                    tools continue. Model decides when to end.
                - `'error'`: Raise a `ToolCallLimitExceededError` exception
                - `'end'`: Stop execution immediately with a `ToolMessage` + AI message
                    for the single tool call that exceeded the limit. Raises
                    `NotImplementedError` if there are multiple parallel tool
                    calls to other tools or multiple pending tool calls.

        Raises:
            ValueError: If both limits are `None`, if `exit_behavior` is invalid,
                or if `run_limit` exceeds `thread_limit`.
        """
        super().__init__()

        if thread_limit is None and run_limit is None:
            msg = "At least one limit must be specified (thread_limit or run_limit)"
            raise ValueError(msg)

        valid_behaviors = ("continue", "error", "end")
        if exit_behavior not in valid_behaviors:
            msg = f"Invalid exit_behavior: {exit_behavior!r}. Must be one of {valid_behaviors}"
            raise ValueError(msg)

        if thread_limit is not None and run_limit is not None and run_limit > thread_limit:
            msg = (
                f"run_limit ({run_limit}) cannot exceed thread_limit ({thread_limit}). "
                "The run limit should be less than or equal to the thread limit."
            )
            raise ValueError(msg)

        self.tool_name = tool_name
        self.thread_limit = thread_limit
        self.run_limit = run_limit
        self.exit_behavior = exit_behavior