ElevenLabs Agents API + MCP vs Retell AI API + MCP

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.

Retell AI API + MCP

Published per-minute price for every component, from $0.07 a minute all in. Call data kept indefinitely unless retention is set per agent.

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

Retell AI API + MCP

1. Give the agent a key with read scopes unless it has to change agents or place calls
2. Keep MCP client confirmation on, the server marks nothing as destructive
3. Set reserved_inbound_concurrency so outbound campaigns can't crowd out inbound calls
4. Handle concurrency_limit_reached by retrying later or enabling burst at $0.10 a minute extra
5. Set a data retention period on each agent that handles personal data