ElevenLabs Agents API + MCP vs Pipecat PhoneLLM

ElevenLabs Agents API + MCP

API keys scoped to endpoint groups, with per-key credit limits and service accounts. $0.08 a minute excludes LLM tokens and carrier minutes.

Pipecat PhoneLLM

PhoneLLM Mini is callable per token on Workers AI at $0.06 input and $0.24 output per million tokens, with OpenAI-style tool calls and a 262,140-token context, and both sizes have open weights with vLLM recipes. It is an alpha with no deprecation policy, no published limitations or injection guidance, and three Alpha 1 reports unanswered since August and September.

ElevenLabs Agents API + MCP

1. Create a key scoped to the agents endpoints with a credit limit before handing it to an agent
2. Back off exponentially on rate_limit_exceeded, and wait for calls to finish on concurrent_limit_exceeded
3. Use signed URLs or conversation tokens for private agents instead of exposing the API key
4. Set platform_settings.privacy.retention_days where you don't need 2 years of history
5. Pick a low-latency LLM, the pipeline waits on it every turn

Pipecat PhoneLLM

1. Send temperature: 0 on every call. The repositories' generation_config.json samples by default, and Max's sets temperature 1.0
2. For Max, serve with --reasoning-parser nemotron_v3 and send chat_template_kwargs with enable_thinking: true on every request, or the reply lands in reasoning
3. For Mini, serve without a reasoning parser and keep enable_thinking false, as Cloudflare and the card say, or tool calls can be filed under reasoning
4. Confirm bookings, payments and transfers in your own handler before acting on a tool call, since caller speech reaches the model directly
5. Pin the model ID including alpha-2. Daily states no notice period, and a later alpha may replace it