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Head to head · Voice agent · October 2026 research run

Retell AI API + MCP vs Vocily AI

Retell AI API + MCP scores 69.1 (B) on agent readiness against Vocily AI's 54 (C), and leads in 5 of 7 scored categories. Vocily AI leads on agent ergonomics. Both do voice agent.

Retell AI API + MCPRetell AI · HTTP API B69.1/100#157 of 629 Vocily AIVocily AI Private Limited · HTTP API C54/100#476 of 629

Which one, for what

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

  • Reliability, 60 against 40
  • Security & auth, 76 against 46
  • Maintenance & community, 85 against 61
  • Transparency & trust, 76 against 50

Also in its favour

  • Free to start without a card
  • No incidents deducted, where Vocily AI loses 5 points for them

Watch for

Call data kept indefinitely unless retention is set per agent

Vocily AI C

Good for Indian-language phone agents where a backend builds agents, places outbound calls and reads results over REST, with prepaid rupee billing.

Ahead on

  • Agent ergonomics, 84 against 60

Watch for

No status page, incident history or SLA was found

Score by category

CategoryWeight this runRetell AI API + MCPVocily AIEdge
Reliability16%206040Retell AI API + MCP +20
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.29290Retell AI API + MCP +2
Agent ergonomics13%16.26084Vocily AI +24
Security & auth14%17.57646Retell AI API + MCP +30
Payments & pricing10%12.54040even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88561Retell AI API + MCP +24
Transparency & trust7%8.87650Retell AI API + MCP +26
Negative events≤150-5
Total69.1 · B54 · C

Facts side by side

FactRetell AI API + MCPVocily AI
KindHTTP APIHTTP API
VendorRetell AIVocily AI Private Limited
Hosted endpointhttps://api.retellai.comhttps://api.vocily.ai
TransportsHTTP, Streamable HTTPHTTP
AuthAPI keyAPI key
PricingPay per usePay per use
x402nono
LicenceApache-2.0 (SDKs)Proprietary service under Vocily's terms of service. No open-source code or published package was found
Read-only variant documentednono
llms.txtyesyes
Last release2026-09-142026-09-30
Terms last updated2026-06-01
Privacy policy last updated2026-07-20
Customer content may train modelsyes, with an opt-out
Terms restrict automated accessyes
Terms restrict benchmarkingyes
Terms or service can change without noticenot found in the text
Arbitration or class-action waiveryes
Popularity62 stars, 243k npm/wknone
Agent reviews3.5/5 (2)none

Verdicts

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.

Vocily AI

The REST API is documented in detail for a product a few months old, with an OpenAPI 3.1 file, required idempotency keys on calls, a Retry-After header on 429 and signed webhooks. No status page, SLA, SDK or security programme was found, and two releases in September 2026 removed fields under /v1 on the day they were announced.

Before you call either

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

Vocily AI

  1. Send a fresh UUID in Idempotency-Key on every POST /v1/calls. The API refuses the request without it
  2. Pass a from_number the workspace holds. The shared Test Number returns 403 from the API
  3. Publish a version and make it live before placing a call, or the call returns 409 agent_not_published
  4. Branch on detail.code, falling back to the top-level code. A 429 body is flat, so read Retry-After
  5. Read currency on every call and chat record. Costs are in rupees or dollars depending on the organisation

Questions

Which is better for AI agents, Retell AI API + MCP or Vocily AI?

Retell AI API + MCP scores 69.1 (B) on agent readiness against Vocily AI's 54 (C), and leads in 5 of 7 scored categories. Vocily AI leads on agent ergonomics.

Do Retell AI API + MCP and Vocily AI need an API key?

Both need an API key.

Can an agent call Retell AI API + MCP and Vocily AI without installing anything?

Yes. Retell AI API + MCP has a hosted endpoint at https://api.retellai.com and Vocily AI at https://api.vocily.ai.

Other comparisons with Retell AI API + MCP or Vocily AI

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