Why does a token budget no longer cap AI agent spend?
Because the bill now has several meters. A real-time voice session is metered in seconds, an agent sandbox in container time, and tool calls as their own line. A cap expressed only in tokens leaves those meters unmetered, so spend can grow while the token counter looks healthy.
How are real-time voice sessions billed?
OpenAI's GPT-Live 1, released September 10, 2026, is billed at $0.05 per minute, charged per second rather than rounded up to the next minute. Backend model and tool usage triggered by the session is billed separately, so a voice conversation runs on two meters at once. The model is reachable only on v1/live/sessions.
What is billed separately in the OpenAI Agents API?
Agent billing stacks three units: model usage at the selected model's API rates, OpenAI tools at their standard rates, and OpenAI-hosted sandboxes at standard container rates. An agent that spends most of its life waiting in a sandbox carries a cost the token rate does not describe.
Who is accountable for a tool call made by a managed agent?
It depends on the provider. Anthropic's Managed Agents evaluate each agent or MCP tool call server-side under auto permission policies, and the agent.tool_use and agent.mcp_tool_use events report how the call was evaluated — so an approval decision is auditable per call. OpenAI's Agents API leaves permissions, confirmations, private function execution and durable task state with your application.
Are voice endpoints as stable as chat endpoints?
No — they rotate faster. Published lifecycles for voice and realtime endpoints are markedly shorter than for chat models, and some providers have moved to shorter legacy notice periods, including a 45-day option, with access potentially lost after 15 days of inactivity. Business-critical voice traffic belongs on generally available endpoints with the retirement date tracked per provider.