ToolRuntime

Example:

from langchain_core.tools import tool
from langchain.tools import ToolRuntime

@tool
def my_tool(x: int, runtime: ToolRuntime) -> str:
    """Tool that accesses runtime context."""
    # Access state
    messages = tool_runtime.state["messages"]

    # Access tool_call_id
    print(f"Tool call ID: {tool_runtime.tool_call_id}")

    # Access config
    print(f"Run ID: {tool_runtime.config.get('run_id')}")

    # Access runtime context
    user_id = tool_runtime.context.get("user_id")

    # Access store
    tool_runtime.store.put(("metrics",), "count", 1)

    # Stream output
    tool_runtime.stream_writer.write("Processing...")

    return f"Processed {x}"

This is a marker class used for type checking and detection. The actual runtime object will be constructed during tool execution.