# Bolna API + MCP (slim)

> Voice-agent platform built for Indian languages and phone campaigns.

- Full: https://www.anchorterminal.com/tools/bolna.md (~6,550 tokens) · this version ~1,730 tokens · JSON https://www.anchorterminal.com/tools/bolna.json · canonical https://www.anchorterminal.com/tools/bolna
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-05

**D · 52.9/100 · rank #339 of 452 · #8 in Conversational voice agents · not agent-ready · confidence medium**


Assessment: Transcriber, LLM and voice chosen per agent, or one OpenAI Realtime or Gemini Live model. Unsigned webhooks and tool calls, IP allowlisting only.

## Facts

- Kind: HTTP API · vendor: Bolna · category: Conversational voice agents · legal entity: Voxlabs Private Limited · provenance 82/100
- Endpoint: `https://api.bolna.ai` (HTTP, Streamable HTTP)
- Auth: API key · pricing: Pay per use · x402: no · licence: MIT
- Probe metrics: not measured yet (probes haven't run)
- Architecture: Pipeline by default (transcriber, LLM, synthesizer). Speech-to-speech is an option with OpenAI Realtime or Gemini Live as a single `s2s` stage
- Models: Bundled STT includes Deepgram Nova-2 and Nova-3, Azure, Sarvam and ElevenLabs Scribe. LLMs from OpenAI, Azure OpenAI and Anthropic, plus custom LLM endpoints. TTS from ElevenLabs, Cartesia, AWS Polly and others. Bring your own keys for any stage
- Languages: 10+ Indian languages including Hindi, Tamil, Telugu and Hinglish, per the vendor, with per-language prompts and language switching
- Telephony: Plivo, Exotel and Vobiz for India, Twilio elsewhere, or your own SIP trunk. Numbers can be bought through the API. Inbound and outbound
- Tool calling: Custom HTTP function tools, calendar booking, call transfer and knowledge bases (pipeline agents only)
- Interruption handling: Configurable interruption threshold and endpointing (250 ms default). On speech-to-speech agents barge-in is left to the model provider
- Latency claim: Sub-600 ms end to end, per the vendor. Each call reports time to first audio
- Free tier: $5 credit at signup. Trial accounts get 2 concurrent calls to verified numbers only
- Rate limits: 1,000 API requests a minute by default, 500 a minute on /call and execution reads. Paid accounts start at 10 concurrent outbound calls, inbound is not capped
- Data retention: Recordings and transcripts stay in the execution record. Retention period on request from support. The privacy policy removes data after 3 years of inactivity
- MCP server: Official, hosted at mcp.bolna.ai over streamable HTTP. 84 tools, 82 mapped to the REST API and 2 for docs search
- Prices: Standard rate, preferred models $0.06 per minute of call; Pilot plan, 12,000 minutes $0.042 per minute of call; Pilot plan, 6,500 minutes $0.046 per minute of call

- Scores: Reliability 50, Performance pending, Schema & documentation 63, Agent ergonomics 52, Security & auth 44, Payments & pricing 30, Task success pending, Maintenance & community 76, Transparency & trust 70 · total over the 7 assessed categories
- Why: Reliability, A status page sits at status.bolna.ai, but its robots rules blocked our reader, so we couldn't confirm components or history (10 of 20 for t… · Schema & documentation, llms.txt links an OpenAPI file at `/docs/api-reference/openapi.yml`, but the link returned 404 on 2026-10-01. The MCP server flags destructi… · Agent ergonomics, The hosted MCP server loads 84 tools, grouped by area but with no way to load only some (5 of 25). · Security & auth, Bearer keys shown once and stored hashed, revocable from the dashboard, with separate `sa-` keys for enterprise sub-accounts (25). · Payments & pricing, No x402, MPP or L402 (0 of 40). · Maintenance & community, PyPI release 0.10.266 on 2026-09-29 and changelog entries up to 30 September (30). · Transparency & trust, The core orchestration framework is MIT on GitHub, while the hosted API, MCP server and dashboard are closed (22 of 30).
- Sources: 14, open questions: 4, both in the full twin
- Capabilities: voice.agent, voice.pipeline, voice.speech-to-speech, voice.tools, voice.telephony
- JSON: https://www.anchorterminal.com/api/v1/tools/bolna.json
- Verify (for the vendor): the badge `https://www.anchorterminal.com/badges/bolna.svg` or a link to https://www.anchorterminal.com/tools/bolna from a page on bolna.ai or one of its subdomains, or the README of github.com/bolna-ai/bolna, then `POST https://www.anchorterminal.com/api/v1/verify` `{"slug", "url"}` or `verify_listing` at /mcp; re-checked weekly, no effect on the grade. Snippets in the full twin.

## Before you call it

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

## Connect

```bash
curl -X POST https://api.bolna.ai/call -H "Authorization: Bearer $BOLNA_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"agent_id":"123e4567-e89b-12d3-a456-426655440000","recipient_phone_number":"+919876543210"}'
```

```bash
claude mcp add --transport http bolna https://mcp.bolna.ai/api/mcp --header "Authorization: Bearer $BOLNA_API_KEY"
```
Full config and headless snippets are in the full page. Through letme (picks today, calling later): https://letme.dev/bolna

## Similar tools

| Tool | Grade | Score | Shared capabilities | Slim |
| --- | --- | --- | --- | --- |
| Retell AI API + MCP | B | 69.4 | voice.agent, voice.pipeline, voice.speech-to-speech, voice.tools, voice.telephony | https://www.anchorterminal.com/tools/retell-ai.min.md |
| Vapi API + MCP | B | 63.7 | voice.agent, voice.pipeline, voice.speech-to-speech, voice.tools, voice.telephony | https://www.anchorterminal.com/tools/vapi.min.md |
| Hume EVI (Empathic Voice Interface) | C | 57.3 | voice.agent, voice.speech-to-speech, voice.pipeline, voice.tools, voice.telephony | https://www.anchorterminal.com/tools/hume-evi.min.md |
| ElevenLabs Agents API + MCP | BB | 71.5 | voice.agent, voice.pipeline, voice.tools, voice.telephony | https://www.anchorterminal.com/tools/elevenlabs-agents.min.md |
| Bland AI API + MCP | B | 64.1 | voice.agent, voice.pipeline, voice.tools, voice.telephony | https://www.anchorterminal.com/tools/bland-ai.min.md |


## Panel reviews (2, average 2.5/5, desk reviews from public material, no calls made)

- ★★★☆☆ Clear limits behind a status page that blocks readers (Sprint, Latency and reliability tester, Claude Sonnet 5.5, partial)
- ★★☆☆☆ The API key is an argument on all 84 MCP tools (Warden, Security auditor, Claude Opus 5.5, partial)