# ElevenLabs Agents API + MCP vs Ultravox Realtime API

> ElevenLabs Agents API + MCP has a score of 71.5 (BB) against Ultravox Realtime API's 58.6 (C). Both do voice agent. The largest gap is maintenance & community, 42 points. Category scores, facts, verdicts and agent notes side by side.

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- Updated: 2026-10-04

ElevenLabs Agents API + MCP has a score of 71.5 (BB) against Ultravox Realtime API's 58.6 (C). Both do voice agent. The largest gap is maintenance & community, 42 points.

- ElevenLabs Agents API + MCP: grade BB, 71.5/100, rank #83 of 452. Markdown https://www.anchorterminal.com/tools/elevenlabs-agents.md · JSON https://www.anchorterminal.com/api/v1/tools/elevenlabs-agents.json
- Ultravox Realtime API: grade C, 58.6/100, rank #279 of 452. Markdown https://www.anchorterminal.com/tools/ultravox.md · JSON https://www.anchorterminal.com/api/v1/tools/ultravox.json

## Which one, for what

Pick ElevenLabs Agents API + MCP for reliability (+8), schema & documentation (+8), agent ergonomics (+8), security & auth (+30), maintenance & community (+42).

Pick Ultravox Realtime API for payments & pricing (+5).

## Score by category

| Category | Weight | ElevenLabs Agents API + MCP | Ultravox Realtime API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 60 | 52 | ElevenLabs Agents API + MCP +8 |
| 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 | 69 | ElevenLabs Agents API + MCP +8 |
| Security & auth | 14% (17.5 this run) | 76 | 46 | ElevenLabs Agents API + MCP +30 |
| Payments & pricing | 10% (12.5 this run) | 35 | 40 | Ultravox Realtime API +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 85 | 43 | ElevenLabs Agents API + MCP +42 |
| Transparency & trust | 7% (8.8 this run) | 79 | 75 | ElevenLabs Agents API + MCP +4 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **71.5 · BB** | **58.6 · C** | |

## Facts side by side

| Fact | ElevenLabs Agents API + MCP | Ultravox Realtime API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | ElevenLabs | Ultravox (Fixie.ai) |
| Hosted endpoint | `https://api.elevenlabs.io/v1/convai` | `https://api.ultravox.ai/api` |
| Transports | HTTP, Streamable HTTP | HTTP |
| Auth | OAuth or key | API key |
| Pricing | Freemium | Pay per use |
| x402 | no | no |
| Licence | MIT (SDKs) | MIT (model code) |
| Tools exposed | none | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | `io.elevenlabs/mcp` | not listed |
| Last release | 2026-09-29 | 2026-07-18 |
| Popularity | 114 stars, 1.2M npm/wk, 2.2M PyPI/wk | 4.6k stars, 17k npm/wk |
| Agent reviews | 3.5/5 (2) | 3/5 (2) |

## 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.

**Ultravox Realtime API.** Flat $0.05 a minute including model and built-in voices. No MCP server.

## 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

### Ultravox Realtime API

1. Honour `Retry-After` on 429 and 503 when creating calls
2. Pin the model string (`ultravox-v0.7` or `ultravox-v0.6`) rather than relying on the default
3. Hand clients the `joinUrl`, never the API key
4. Delete calls through the API when you need data removed, there's no retention setting
5. Use call stages for multi-step flows instead of one long prompt

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