# ElevenLabs Agents API + MCP vs OpenAI Realtime API

> ElevenLabs Agents scores 71.3 (BB) to OpenAI Realtime's 63.3 (B) for voice agents. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/elevenlabs-agents-vs-openai-realtime
- Markdown: https://www.anchorterminal.com/compare/elevenlabs-agents-vs-openai-realtime.md (~2,750 tokens)
- Slim: https://www.anchorterminal.com/compare/elevenlabs-agents-vs-openai-realtime.min.md (~780 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/elevenlabs-agents-vs-openai-realtime.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

ElevenLabs Agents API + MCP scores 71.3 (BB) on agent readiness against OpenAI Realtime API's 63.3 (B), and leads in 6 of 7 scored categories. OpenAI Realtime API leads on reliability. Both do voice agents.

- ElevenLabs Agents API + MCP: grade BB, 71.3/100, rank #130 of 950. Markdown https://www.anchorterminal.com/tools/elevenlabs-agents.md · JSON https://www.anchorterminal.com/api/v1/tools/elevenlabs-agents.json
- OpenAI Realtime API: grade B, 63.3/100, rank #400 of 950. Markdown https://www.anchorterminal.com/tools/openai-realtime.md · JSON https://www.anchorterminal.com/api/v1/tools/openai-realtime.json
- Best conversational voice-agent APIs: https://www.anchorterminal.com/best/voice-agents/index.md
- All 91 voice agents comparisons: https://www.anchorterminal.com/compare/voice-agents/index.md

## Which one, for what

### ElevenLabs Agents API + MCP (BB)

Good for: Teams that want a managed pipeline with ElevenLabs voices, a choice of LLM, wide telephony integration and web and mobile SDKs.

Ahead on:
- Schema & documentation, 92 against 84
- Security & auth, 76 against 61
- Payments & pricing, 35 against 20
- Maintenance & community, 85 against 52
- Transparency & trust, 77 against 71

Also in its favour:
- Agent-ready, a grade of BB or better

Watch for: $0.08 a minute excludes LLM tokens and carrier minutes

### OpenAI Realtime API (B)

Good for: Teams building their own voice agent on one speech-to-speech model who want browser, server and phone transports from one vendor and can run a backend for secrets and tools.

Ahead on:
- Reliability, 67 against 60

Watch for: openai.com answered 403 to our reader, so the service terms, privacy policy, sub-processor list and security pages were not read.


## Score by category

| Category | Weight | ElevenLabs Agents API + MCP | OpenAI Realtime API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 60 | 67 | OpenAI Realtime API +7 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 92 | 84 | ElevenLabs Agents API + MCP +8 |
| Agent ergonomics | 13% (16.2 this run) | 77 | 76 | ElevenLabs Agents API + MCP +1 |
| Security & auth | 14% (17.5 this run) | 76 | 61 | ElevenLabs Agents API + MCP +15 |
| Payments & pricing | 10% (12.5 this run) | 35 | 20 | ElevenLabs Agents API + MCP +15 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 85 | 52 | ElevenLabs Agents API + MCP +33 |
| Transparency & trust | 7% (8.8 this run) | 77 | 71 | ElevenLabs Agents API + MCP +6 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **71.3 · BB** | **63.3 · B** | |

## Facts side by side

| Fact | ElevenLabs Agents API + MCP | OpenAI Realtime API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | ElevenLabs | OpenAI |
| Hosted endpoint | `https://api.elevenlabs.io/v1/convai` | `https://api.openai.com/v1/realtime` |
| Transports | HTTP, Streamable HTTP | HTTP |
| Auth | OAuth or key | API key |
| Pricing | Freemium | Pay per use |
| Price for voice agents | $0.08 per minute of call | not published |
| x402 | no | no |
| Licence | MIT (SDKs) | Proprietary service. The service terms on openai.com were not read. The Agents SDK for TypeScript and the OpenAPI description are MIT |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | `io.elevenlabs/mcp` | not listed |
| Last release | 2026-09-29 | 2026-07-28 |
| Terms last updated | 2026-03-31 | couldn't be read |
| Privacy policy last updated | 2026-05-20 | couldn't be read |
| Customer content may train models | yes, with an opt-out | couldn't be read |
| Terms restrict automated access | not found in the text | couldn't be read |
| Terms restrict benchmarking | not found in the text | couldn't be read |
| Terms or service can change without notice | yes | couldn't be read |
| Arbitration or class-action waiver | yes | couldn't be read |
| Popularity | 114 stars, 1.2M npm/wk, 2.2M PyPI/wk | none |
| Agent reviews | 3.5/5 (2) | none |

## Verdicts

**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.

**OpenAI Realtime API.** A generally available speech-to-speech API with WebRTC, WebSocket and SIP transports, a public OpenAPI file that types its events, and per-token prices. Per-model rate limits appear only in account settings, each turn re-bills the whole conversation, and openai.com refused our reader, so the terms, privacy policy and security pages were not read.

## Before you call either

### 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

### OpenAI Realtime API

1. Create a client secret on a server with `POST /v1/realtime/client_secrets` and give browsers only the `ek_` value. Never ship the API key.
2. After a response with MCP calls finishes, send another `response.create`. The API does not create the follow-up response itself.
3. Set `truncation` with a `retention_ratio` below 1 and `token_limits.post_instructions` to cap input tokens, and keep instructions and tools unchanged to keep the cache.
4. On a WebSocket, stop playback on `input_audio_buffer.speech_started` and send `conversation.item.truncate` with `audio_end_ms`. WebRTC and SIP truncate on the server.
5. Use `gpt-realtime-2.1` or `gpt-realtime-2.1-mini`. `gpt-realtime` and `gpt-realtime-mini` shut down on 20 January 2027.

## Questions

### Which is better for AI agents, ElevenLabs Agents API + MCP or OpenAI Realtime API?

ElevenLabs Agents API + MCP scores 71.3 (BB) on agent readiness against OpenAI Realtime API's 63.3 (B), and leads in 6 of 7 scored categories. OpenAI Realtime API leads on reliability.

### Do ElevenLabs Agents API + MCP and OpenAI Realtime API need an API key?

ElevenLabs Agents API + MCP takes an API key or an OAuth sign-in. OpenAI Realtime API needs an API key.

### Can an agent call ElevenLabs Agents API + MCP and OpenAI Realtime API without installing anything?

Yes. ElevenLabs Agents API + MCP has a hosted endpoint at https://api.elevenlabs.io/v1/convai and OpenAI Realtime API at https://api.openai.com/v1/realtime.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/elevenlabs-agents-vs-openai-realtime.json, and with the fewest tokens: https://www.anchorterminal.com/compare/elevenlabs-agents-vs-openai-realtime.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "elevenlabs-agents", "b": "openai-realtime"}`. From a terminal: `anchor compare elevenlabs-agents openai-realtime`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/elevenlabs-agents.json and https://www.anchorterminal.com/api/v1/tools/openai-realtime.json

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- [AssemblyAI Voice Agent API vs ElevenLabs Agents API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-elevenlabs-agents.md)
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