tool_retry.py — langchain Source File

Source Code

"""Tool retry middleware for agents."""

from __future__ import annotations

import asyncio
import time
import warnings
from typing import TYPE_CHECKING, Any

from langchain_core.messages import ToolMessage

from langchain.agents.middleware._retry import (
    OnFailure,
    RetryOn,
    calculate_delay,
    should_retry_exception,
    validate_retry_params,
)
from langchain.agents.middleware.types import AgentMiddleware, AgentState, ContextT, ResponseT

if TYPE_CHECKING:
    from collections.abc import Awaitable, Callable

    from langgraph.types import Command

    from langchain.agents.middleware.types import ToolCallRequest
    from langchain.tools import BaseTool


class ToolRetryMiddleware(AgentMiddleware[AgentState[ResponseT], ContextT, ResponseT]):
    """Middleware that automatically retries failed tool calls with configurable backoff.

    Supports retrying on specific exceptions and exponential backoff.

    Examples:
        !!! example "Basic usage with default settings (2 retries, exponential backoff)"

            ```python
            from langchain.agents import create_agent
            from langchain.agents.middleware import ToolRetryMiddleware

            agent = create_agent(model, tools=[search_tool], middleware=[ToolRetryMiddleware()])
            ```

        !!! example "Retry specific exceptions only"

            ```python
            from requests.exceptions import RequestException, Timeout

            retry = ToolRetryMiddleware(
                max_retries=4,
                retry_on=(RequestException, Timeout),
                backoff_factor=1.5,
            )
            ```

        !!! example "Custom exception filtering"

            ```python
            from requests.exceptions import HTTPError
// ... (344 more lines)