# ElevenLabs Agents API + MCP vs Synthflow API + MCP

> ElevenLabs Agents API + MCP has a score of 71.5 (BB) against Synthflow API + MCP's 51.3 (D). Both do voice agent. The largest gap is payments & pricing, 35 points. Category scores, facts, verdicts and agent notes side by side.

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- 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: 2026-10-05

ElevenLabs Agents API + MCP has a score of 71.5 (BB) against Synthflow API + MCP's 51.3 (D). Both do voice agent. The largest gap is payments & pricing, 35 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
- Synthflow API + MCP: grade D, 51.3/100, rank #352 of 452. Markdown https://www.anchorterminal.com/tools/synthflow.md · JSON https://www.anchorterminal.com/api/v1/tools/synthflow.json

## Which one, for what

Pick ElevenLabs Agents API + MCP for reliability (+15), schema & documentation (+5), agent ergonomics (+32), security & auth (+25), payments & pricing (+35), maintenance & community (+17), transparency & trust (+11).

Pick Synthflow API + MCP for nothing in particular (no category where it leads by five points or more).

## Score by category

| Category | Weight | ElevenLabs Agents API + MCP | Synthflow API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 60 | 45 | ElevenLabs Agents API + MCP +15 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 92 | 87 | ElevenLabs Agents API + MCP +5 |
| Agent ergonomics | 13% (16.2 this run) | 77 | 45 | ElevenLabs Agents API + MCP +32 |
| Security & auth | 14% (17.5 this run) | 76 | 51 | ElevenLabs Agents API + MCP +25 |
| Payments & pricing | 10% (12.5 this run) | 35 | 0 | ElevenLabs Agents API + MCP +35 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 85 | 68 | ElevenLabs Agents API + MCP +17 |
| Transparency & trust | 7% (8.8 this run) | 79 | 68 | ElevenLabs Agents API + MCP +11 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **71.5 · BB** | **51.3 · D** | |

## Facts side by side

| Fact | ElevenLabs Agents API + MCP | Synthflow API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | ElevenLabs | Synthflow |
| Hosted endpoint | `https://api.elevenlabs.io/v1/convai` | `https://api.synthflow.ai/v2` |
| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Paid |
| x402 | no | no |
| Licence | MIT (SDKs) | none |
| Tools exposed | none | 60 |
| 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 | 2026-10-01 |
| Popularity | 114 stars, 1.2M npm/wk, 2.2M PyPI/wk | none |
| Agent reviews | 3.5/5 (2) | 2/5 (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.

**Synthflow API + MCP.** Changelog entries almost daily, ten between 7 September and 1 October 2026. Sales-led only, contracts from $30,000 a year, no free tier.

## 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

### Synthflow API + MCP

1. Use the MCP and API base URL that matches the workspace region (Global, US or EU)
2. Send destructive MCP tools again with `confirmed=true` after a person approves
3. Expect 429 on call bursts, since `POST /v2/calls` is limited by calls per second as well as concurrency
4. Read the transfer failure reason on a failed transfer before retrying it

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