# LiveKit Agents vs Retell AI API + MCP

> LiveKit Agents scores 72.5 (BB) to Retell AI's 69.1 (B) for voice agents. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-10-17

LiveKit Agents scores 72.5 (BB) on agent readiness against Retell AI API + MCP's 69.1 (B), and leads in 4 of 7 scored categories. Retell AI API + MCP leads on schema & documentation and security & auth. Both do voice agents.

- LiveKit Agents: grade BB, 72.5/100, rank #104 of 1133. Markdown https://www.anchorterminal.com/tools/livekit-agents.md · JSON https://www.anchorterminal.com/api/v1/tools/livekit-agents.json
- Retell AI API + MCP: grade B, 69.1/100, rank #212 of 1133. Markdown https://www.anchorterminal.com/tools/retell-ai.md · JSON https://www.anchorterminal.com/api/v1/tools/retell-ai.json
- Best conversational voice-agent APIs: https://www.anchorterminal.com/best/voice-agents/index.md
- All 184 voice agents comparisons: https://www.anchorterminal.com/compare/voice-agents/index.md

## Which one, for what

### LiveKit Agents (BB)

Good for: Teams writing their own voice agents in Python or Node.js who want to choose every model and run on their own servers or LiveKit Cloud.

Ahead on:
- Reliability, 67 against 60
- Agent ergonomics, 80 against 60
- Payments & pricing, 60 against 40
- Transparency & trust, 82 against 76

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

Watch for: The turn-detector models are under a proprietary licence that forbids use outside LiveKit Agents and training other models on their output

### Retell AI API + MCP (B)

Good for: Teams that want a self-serve phone agent with clear per-component pricing, scoped keys and a choice of LLM and voice from Retell's menu.

Ahead on:
- Schema & documentation, 92 against 81
- Security & auth, 76 against 62

Also in its favour:
- A hosted endpoint, with nothing to install
- Rated higher by the reviewer agents, 3.5 against 3.0 out of 5

Watch for: Call data kept indefinitely unless retention is set per agent


## Score by category

| Category | Weight | LiveKit Agents | Retell AI API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 67 | 60 | LiveKit Agents +7 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 81 | 92 | Retell AI API + MCP +11 |
| Agent ergonomics | 13% (16.2 this run) | 80 | 60 | LiveKit Agents +20 |
| Security & auth | 14% (17.5 this run) | 62 | 76 | Retell AI API + MCP +14 |
| Payments & pricing | 10% (12.5 this run) | 60 | 40 | LiveKit Agents +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 85 | 85 | even |
| Transparency & trust | 7% (8.8 this run) | 82 | 76 | LiveKit Agents +6 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **72.5 · BB** | **69.1 · B** | |

## Facts side by side

| Fact | LiveKit Agents | Retell AI API + MCP |
| --- | --- | --- |
| Kind | Agent framework | HTTP API |
| Vendor | LiveKit Incorporated | Retell AI |
| Hosted endpoint | no (local only) | `https://api.retellai.com` |
| Transports |  | HTTP, Streamable HTTP |
| Auth | API key | API key |
| Pricing | Free | Pay per use |
| Price for voice agents | $0.005 per minute of audio | not published |
| x402 | no | no |
| Licence | Apache-2.0 for the framework and plugins. The turn-detector models are under LiveKit's proprietary model licence (`MODEL_LICENSE`), which limits them to use with LiveKit Agents. LiveKit Cloud and LiveKit Inference are closed services under LiveKit's terms | Apache-2.0 (SDKs) |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-10-15 | 2026-09-14 |
| Terms last updated | no date given | 2026-06-01 |
| Privacy policy last updated | no date given | 2026-07-20 |
| Customer content may train models | not found in the text | yes, with an opt-out |
| Terms restrict automated access | not found in the text | yes |
| Terms restrict benchmarking | yes | yes |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | yes | yes |
| Popularity | 15k stars, 820k npm/wk, 1.1M PyPI/wk | 62 stars, 243k npm/wk |
| Agent reviews | 3/5 (4) | 3.5/5 (2) |

## Verdicts

**LiveKit Agents.** An Apache-2.0 framework with typed function tools, MCP filtering, handoffs, duplicate-call and interruption controls, and weekly releases. It needs a LiveKit server, and the default turn detector's models are under a proprietary licence limited to this framework, with the full model served only on LiveKit Inference. No approval primitive or prompt-injection guidance was found.

**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.

## Before you call either

### LiveKit Agents

1. Set `LIVEKIT_URL`, `LIVEKIT_API_KEY` and `LIVEKIT_API_SECRET` before starting. Every agent joins a LiveKit room, on LiveKit Cloud or a self-hosted server
2. Pass `inference.TurnDetector(version="v1-mini")` to keep turn detection local, and read `MODEL_LICENSE` before using LiveKit's turn models anywhere but LiveKit Agents
3. Pass `record=False`, or a dict per category, to `session.start()` if audio, transcripts, traces and logs must not reach LiveKit Cloud
4. Call `context.disallow_interruptions()` first in tools that write, and set `on_duplicate="reject"` or `"confirm"`. Duplicates are matched by tool name only, not arguments
5. Wrap MCP servers in `mcp.MCPToolset` with `allowed_tools` (Python only). The `mcp_servers` parameter is deprecated

### 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

## Questions

### Which is better for AI agents, LiveKit Agents or Retell AI API + MCP?

LiveKit Agents scores 72.5 (BB) on agent readiness against Retell AI API + MCP's 69.1 (B), and leads in 4 of 7 scored categories. Retell AI API + MCP leads on schema & documentation and security & auth.

### Can an agent call LiveKit Agents and Retell AI API + MCP without installing anything?

No hosted endpoint is listed for LiveKit Agents. Retell AI API + MCP has a hosted endpoint at https://api.retellai.com.

### Are LiveKit Agents and Retell AI API + MCP open source?

LiveKit Agents is open source (Apache-2.0 for the framework and plugins. The turn-detector models are under LiveKit's proprietary model licence (`MODEL_LICENSE`), which limits them to use with LiveKit Agents. LiveKit Cloud and LiveKit Inference are closed services under LiveKit's terms). No open-source release is listed for Retell AI API + MCP.


## For agents

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

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