Why would a developer use Anthropic's token counting API endpoint before sending a message?
Select an answer to reveal the explanation.
Short Explanation and Infographic
The count_tokens endpoint lets you measure your prompt size before sending it — avoids errors from exceeding context limits and helps estimate costs in advance.
Full explanation below image
Full Explanation
Anthropic provides a token counting endpoint that accepts the same message structure as the messages endpoint but returns token counts instead of generating a response. Developers use it to: verify a prompt fits within the model's context window before sending, estimate API costs before making expensive calls, and dynamically manage context by trimming content that would exceed limits. Option A is wrong — token counting is optional, not a required authorization step. Option C confuses with CSRF tokens (a web security concept). Option D is wrong — while usage_metadata in responses reports token counts after the fact, the counting endpoint allows pre-flight checks.