gemini-3.1-flash-tts-preview

Fined:

• fatal · currency — dropped the minus sign (7 of 7 transcripts)

→ we sent “A refund of -$0.99 was applied.”

→ it said “A refund of $0.99 was applied.”

• minor · dates · promptable — kept the value but never said “july” (7 of 23 transcripts)

→ we sent “Your appointment is on 07/15/2026.”

→ it said “Your appointment is on seven fifteen, twenty twenty six.”

• minor · formatting · promptable — said “agent id” out loud (18 of 37 transcripts)

→ we sent “Transferring you now. <call:transfer agent_id="agent_7"/>”

→ it said “Transferring you now. Call: Transfer Agent ID: Agent 7.”

+ 3 more fined

Token-billed: $1/1M text in, $20/1M audio out; Google states 25 audio tokens/sec (ai.google.dev/gemini-api/docs/pricing). At 900 chars/min of speech that is ~$33 per 1M chars; text-in adds ~$0.25, negligible.