UsageMetadata

Breakdown of input token counts.

Does not need to sum to full input token count. Does not need to have all keys.

Count of input (or prompt) tokens. Sum of all input token types.

Breakdown of output token counts.

Does not need to sum to full output token count. Does not need to have all keys.

Count of output (or completion) tokens. Sum of all output token types.

Total token count. Sum of input_tokens + output_tokens.