# AssemblyAI Voice Agent API vs Bland AI API + MCP

> AssemblyAI Voice Agent and Bland AI score within a point of each other for voice agents, 64.4 and 63.8 out of 100. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bland-ai
- Markdown: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bland-ai.md (~2,600 tokens)
- Slim: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bland-ai.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bland-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: 2026-10-09

AssemblyAI Voice Agent API and Bland AI API + MCP score within a point of each other on agent readiness, 64.4 (B) and 63.8 (B). Bland AI API + MCP leads on reliability, payments & pricing and transparency & trust. Both do voice agents.

- AssemblyAI Voice Agent API: grade B, 64.4/100, rank #351 of 950. Markdown https://www.anchorterminal.com/tools/assemblyai-voice-agent.md · JSON https://www.anchorterminal.com/api/v1/tools/assemblyai-voice-agent.json
- Bland AI API + MCP: grade B, 63.8/100, rank #370 of 950. Markdown https://www.anchorterminal.com/tools/bland-ai.md · JSON https://www.anchorterminal.com/api/v1/tools/bland-ai.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

### AssemblyAI Voice Agent API (B)

Good for: A developer who wants one managed pipeline at a flat rate and is content with AssemblyAI's own speech models and voices, with an optional model of their own.

Ahead on:
- Schema & documentation, 83 against 68
- Agent ergonomics, 72 against 53

Watch for: No number is published for the concurrent-session limit that the `concurrency_exceeded` error enforces

### Bland AI API + MCP (B)

Good for: Teams that want one predictable per-minute bill for outbound and inbound phone agents, and personal agents that need their own US number.

Ahead on:
- Reliability, 65 against 60
- Payments & pricing, 65 against 40
- Transparency & trust, 71 against 66

Also in its favour:
- Runs on your own machine

Watch for: No OpenAPI document


## Score by category

| Category | Weight | AssemblyAI Voice Agent API | Bland AI API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 60 | 65 | Bland AI API + MCP +5 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 83 | 68 | AssemblyAI Voice Agent API +15 |
| Agent ergonomics | 13% (16.2 this run) | 72 | 53 | AssemblyAI Voice Agent API +19 |
| Security & auth | 14% (17.5 this run) | 62 | 66 | Bland AI API + MCP +4 |
| Payments & pricing | 10% (12.5 this run) | 40 | 65 | Bland AI API + MCP +25 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 64 | 60 | AssemblyAI Voice Agent API +4 |
| Transparency & trust | 7% (8.8 this run) | 66 | 71 | Bland AI API + MCP +5 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **64.4 · B** | **63.8 · B** | |

## Facts side by side

| Fact | AssemblyAI Voice Agent API | Bland AI API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | AssemblyAI, Inc. | Bland AI |
| Hosted endpoint | `wss://agents.assemblyai.com/v1/ws` | `https://api.bland.ai/v1` |
| Transports | HTTP | HTTP, Streamable HTTP, stdio |
| Auth | API key | API key |
| Pricing | Pay per use | Freemium |
| Price for voice agents | $0.075 per minute of call | $29.99 per month (plan) |
| x402 | no | no |
| Licence | Proprietary service under AssemblyAI's Terms of Service. The two starter repositories on GitHub carry no licence file | none |
| Tools exposed | none | 42 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-08-26 | 2026-09-13 |
| Terms last updated | 2026-07-01 | 2026-08-28 |
| Privacy policy last updated | 2026-05-26 | 2026-06-23 |
| Customer content may train models | yes, with an opt-out | not found in the text |
| Terms restrict automated access | yes | yes |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | not found in the text | yes |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | none | 1.2k npm/wk |
| Agent reviews | none | 3/5 (2) |

## Verdicts

**AssemblyAI Voice Agent API.** One $0.075 a minute rate covers speech-to-text, the managed model, speech output, recordings and hosting, and the socket has an AsyncAPI file, typed error codes and a 30-second resume window. No concurrent-session limit is published, the status page has no Voice Agent component, and phone calls are inbound only through a Twilio trunk the customer owns.

**Bland AI API + MCP.** One per-minute rate covering STT, LLM, TTS and telephony, $0.14 on Start and $0.12 on Build. No OpenAPI document.

## Before you call either

### AssemblyAI Voice Agent API

1. Send `session.end` before closing the socket. Without it the session stays resumable, and billed, for 30 seconds
2. Retry only `at_capacity`, `concurrency_exceeded` and `internal_error`, with backoff. Every other session error code is fatal
3. Send `tool.result` inside the `reply.done` handler, not straight after `tool.call`
4. Mint a one-time token with `GET /v1/token` for browser clients and never ship the API key to a page
5. Deduplicate webhooks on `event_id`, and verify `X-AAI-Signature` against the raw body bytes because a 401 is not retried

### Bland AI API + MCP

1. Call `wait_for_call` (it waits up to 45 seconds) instead of polling `get_call_log`
2. Send destructive MCP tools a second time with the confirmation argument
3. Space calls to the same number at least 10 seconds apart or expect a 429
4. Budget $0.015 for every outbound attempt, including ones that never connect
5. Run `validate_pathway` before saving a pathway graph

## Questions

### Which is better for AI agents, AssemblyAI Voice Agent API or Bland AI API + MCP?

AssemblyAI Voice Agent API and Bland AI API + MCP score within a point of each other on agent readiness, 64.4 (B) and 63.8 (B). Bland AI API + MCP leads on reliability, payments & pricing and transparency & trust.

### Do AssemblyAI Voice Agent API and Bland AI API + MCP need an API key?

Both need an API key.

### Can an agent call AssemblyAI Voice Agent API and Bland AI API + MCP without installing anything?

Yes. AssemblyAI Voice Agent API has a hosted endpoint at wss://agents.assemblyai.com/v1/ws and Bland AI API + MCP at https://api.bland.ai/v1.


## For agents

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

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