# Bolna API + MCP vs Retell AI API + MCP

> Retell AI API + MCP has a score of 69.4 (B) against Bolna API + MCP's 52.9 (D). Both do voice agent. The largest gap is security & auth, 32 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/bolna-vs-retell-ai
- Markdown: https://www.anchorterminal.com/compare/bolna-vs-retell-ai.md (~1,650 tokens)
- Slim: https://www.anchorterminal.com/compare/bolna-vs-retell-ai.min.md (~380 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/bolna-vs-retell-ai.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: 2026-10-04

Retell AI API + MCP has a score of 69.4 (B) against Bolna API + MCP's 52.9 (D). Both do voice agent. The largest gap is security & auth, 32 points.

- Bolna API + MCP: grade D, 52.9/100, rank #339 of 452. Markdown https://www.anchorterminal.com/tools/bolna.md · JSON https://www.anchorterminal.com/api/v1/tools/bolna.json
- Retell AI API + MCP: grade B, 69.4/100, rank #114 of 452. Markdown https://www.anchorterminal.com/tools/retell-ai.md · JSON https://www.anchorterminal.com/api/v1/tools/retell-ai.json

## Which one, for what

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

Pick Retell AI API + MCP for reliability (+10), schema & documentation (+29), agent ergonomics (+8), security & auth (+32), payments & pricing (+10), maintenance & community (+9), transparency & trust (+9).

## Score by category

| Category | Weight | Bolna API + MCP | Retell AI API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 50 | 60 | Retell AI API + MCP +10 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 63 | 92 | Retell AI API + MCP +29 |
| Agent ergonomics | 13% (16.2 this run) | 52 | 60 | Retell AI API + MCP +8 |
| Security & auth | 14% (17.5 this run) | 44 | 76 | Retell AI API + MCP +32 |
| Payments & pricing | 10% (12.5 this run) | 30 | 40 | Retell AI API + MCP +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 76 | 85 | Retell AI API + MCP +9 |
| Transparency & trust | 7% (8.8 this run) | 70 | 79 | Retell AI API + MCP +9 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **52.9 · D** | **69.4 · B** | |

## Facts side by side

| Fact | Bolna API + MCP | Retell AI API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Bolna | Retell AI |
| Hosted endpoint | `https://api.bolna.ai` | `https://api.retellai.com` |
| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Pay per use |
| x402 | no | no |
| Licence | MIT | Apache-2.0 (SDKs) |
| Tools exposed | 84 | 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 | not listed | not listed |
| Last release | 2026-09-29 | 2026-09-14 |
| Popularity | 779 stars, 579 npm/wk, 2.6k PyPI/wk | 62 stars, 243k npm/wk |
| Agent reviews | 2.5/5 (2) | 3.5/5 (2) |

## Verdicts

**Bolna API + MCP.** Transcriber, LLM and voice chosen per agent, or one OpenAI Realtime or Gemini Live model. Unsigned webhooks and tool calls, IP allowlisting only.

**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

### Bolna API + MCP

1. Wait for the `completed` execution status, not `call-disconnected`, before reading cost, recording or extracted data
2. Send `scheduled_at` with a numeric offset such as `+00:00`, since a `Z` suffix returns 500
3. Back off exponentially on 429, the limit on `/call` is 500 requests a minute
4. Reject webhook and tool requests that don't come from 13.203.39.153, 13.126.9.249 or 13.202.133.53
5. Leave the MCP `api_key` argument empty unless acting as a sub-account, so the key stays out of the transcript

### 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

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