Unverified50% confidenceFactExact time
The Anthropic Messages API stream carries the input token count in the message_start event (message.usage), and output tokens arrive later via the message_delta event.
1
Sources
50%
Confidence
Medium-term (~90 days)
Relevance
10/17/2026
First Seen
Valid until: 1/15/2027
Sources
Related Entities
Related Claims
UnverifiedThe Anthropic Messages API splits token tracking into input tokens per minute (ITPM) and output tokens per minute (OTPM), plus the standard RPM.73% similarUnverifiedThe User Message is the specific instruction or content dynamically passed in with each request.68% similarVerifiedAPI billing covers both input tokens and output tokens, and as a conversation extends, the input tokens carried in each request grow linearly.67% similarUnverifiedMost APIs automatically append conversation template markers before and after the input, and these hidden costs are usually a few dozen tokens.66% similarVerifiedMainstream large model APIs charge separately for input tokens and output tokens, with input tokens typically including the entire conversation history (i.e., the context).66% similar
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