get_usage_metadata_callback(
name: str = 'usage_metadata_callback'
) -> Generator[UsageMetadataCallbackHandler, None, None]| Name | Type | Description |
|---|---|---|
name | str | Default: 'usage_metadata_callback'The name of the context variable. |
Get usage metadata callback.
Get context manager for tracking usage metadata across chat model calls using
AIMessage.usage_metadata.
Example:
from langchain.chat_models import init_chat_model
from langchain_core.callbacks import get_usage_metadata_callback
llm_1 = init_chat_model(model="openai:gpt-5.5")
llm_2 = init_chat_model(model="anthropic:claude-haiku-4-5-20251001")
with get_usage_metadata_callback() as cb:
llm_1.invoke("Hello")
llm_2.invoke("Hello")
print(cb.usage_metadata)