Cartesia Sonic TTS API + MCP vs MiniMax Speech (T2A)

Cartesia Sonic TTS API + MCP 84

Read as a model, on the lines deepgram-tts, gladia-stt and cartesia-ink-stt use for hosted speech models (recency 30, dated releases 10, deprecation notice 10, support 15, issues 10, SDKs 15, health 10). cartesia-mcp, whose text_to_speech tool calls Sonic, released 0.28.1 on 30 October 2026 after 0.27.0 (20 October), 0.27.1 (23 October) and 0.28.0 (27 October), and sonic-3.6-2026-08-27 is the newest snapshot (30). From 4 August the Python and TypeScript SDKs released 4.0.0, 4.0.1, 4.1.0 and 4.2.0 (14 August to 2 September) and the MCP server more than ten releases (10). Sonic-2, Sonic Turbo and sonic-3-2025-10-27 were sunset after 20 October 2026, announced in the July changelog, about 83 days ahead. The deprecations page dates each sunset but states no minimum notice period (5 of 10). The changelog has Text-to-Speech entries every month from May to September 2026, dated by month only, and no October entry, the same reading as cartesia-ink-stt (11 of 15; was 5). The Python SDK repository had 4 open issues on 9 October per the cartesia-ink-stt check, not re-read on 2 November since GitHub's pages answered 403 (5 of 10; was 7 on a 1 October count of one). Official cartesia and @cartesia/cartesia-js SDKs at 4.2.0 (2 September 2026), generated for API version 2026-08-14 (15). CI, release-please and lock files in both SDK repositories, with dependency updates merged on 23 October (8 of 10). 30+10+5+11+5+15+8 = 84.

MiniMax Speech (T2A) 38

Read as a model, as minimax-voice-cloning is. The newest dated change touching speech is the MCP servers' August update, minimax-mcp-js 0.0.18 on 21 August 2026, 77 days before 6 November, and Speech 2.8 dates from 23 January 2026 (20 of 30). No dated API entries in the last 90 days (0). Support by email and Discord, not tested (6 of 15). No official SDK for speech; the MCP servers expose text_to_audio and list_voices (8 of 15). The Python MCP server has tests and moved to version 2 of the MCP SDK in August, with no CI workflow (4 of 10). Total 38.

Cartesia Sonic TTS API + MCP 47

Model reading of the checklist (credential, training, retention, operator visibility, programme), on the same evidence and values as cartesia-ink-stt. Standard and admin API keys are separate types, revocable, and a server can mint short-lived access tokens with TTS, STT and agent grants, but no key is scoped to TTS (26). Browsers pass the access token in the WebSocket query string, which the authentication guide documents ("In browsers, use an access token and query parameters instead"), and this run takes the full 10 off for a reusable token in a URL, as for cartesia-ink-stt and every Google API listing (16 of 30; the 1 October check didn't deduct). The Terms (last revised 14 June 2024, re-read on 2 November) say inputs, outputs and interactions may be used to train models unless otherwise agreed, with an opt-out form (5 of 20, aligned with cartesia-ink-stt; was 10). Zero data retention is Enterprise only and no retention period is published for other plans (5 of 15). Credit usage and key metadata are readable through admin endpoints and the usage dashboard, no per-call audit log found (7 of 15, aligned; was 8). security.txt at www.cartesia.ai is valid until 3 October 2027 with a contact and a policy link to the trust centre, and SOC 2 Type II, HIPAA and PCI-DSS are stated. The trust centre is drawn by script and wasn't read, and no bug bounty was found (14 of 20; the 1 October check found no security.txt, 10). 16+5+5+7+14 = 47.

MiniMax Speech (T2A) 36

Model reading of the checklist, with training and retention in place of the least-privilege and injection lines. Plain API keys with no scopes found, and leaked keys may be disabled (20 of 30). The terms (effective 30 March 2026), as read for minimax-voice-cloning on 4 November, let MiniMax use input and generated content to operate, maintain, develop and improve its services, with no opt-out found, and the privacy policy rules out only training to profile or target consumers (5 of 20). The speech docs call every interface stateless, and no retention period for submitted text or generated audio was found (5 of 15). Responses carry usage_characters and a trace ID, with no audit log (6 of 15). No security.txt, disclosure policy, bug bounty or certification found (0 of 20). Total 36.

Cartesia Sonic TTS API + MCP 30

No x402, MPP or L402 (0). Plan prices and credit allowances are public, about 1 credit a character, but there's no plain dollar price per character outside the plans (10). Free plan with 20,000 credits a month (about 27 minutes), no card step mentioned, non-commercial use only (20). A person signs up in a browser (0).

MiniMax Speech (T2A) 20

No x402, MPP or L402 (0). Per-character prices for every speech model published without a login (20). No free allowance for synthesis is published (0). A person signs up in a browser and funds a balance (0). Total 20.

Cartesia Sonic TTS API + MCP 65

API reading of the checklist. WAV, MP3 or raw PCM from 8 to 48 kHz, over bytes, SSE or a WebSocket that takes streamed LLM text, with word timestamps on request (22 of 25). Voice lists paginate with SDK iterators, filters not confirmed, and no per-request length cap is documented (10 of 20). Errors are HTTP statuses mapped to SDK exceptions without TTS-specific codes (10 of 20). The SDK retries 429 and 5xx with backoff. We found no seed and didn't confirm the billing rule for failed calls (10 of 20). Four required fields plus the version header, and official Python and TypeScript SDKs (13 of 15).

MiniMax Speech (T2A) 56

API reading of the checklist. Audio comes back hex-encoded inside JSON by default, with subtitles opt-in and format, bitrate and sample rate settable (15 of 25). Voices are listed by type through POST /v1/get_voice, which has no pagination and returns 300+ system voices for all (10 of 20). Errors come as numeric codes in base_resp with a short remedy for each, inside responses documented only as 200 (13 of 20). No idempotency key, and the MCP tools carry no read-only or destructive annotations (10 of 20). Two required fields. No official SDK for speech, with MCP servers in Python and JavaScript (8 of 15). Total 56.

Cartesia Sonic TTS API + MCP 73

Closed service with clear terms, SDKs under Apache-2.0 (15). Privacy policy dated 14 June 2024 and a DPA with 90 and 180 day post-termination windows, but the Terms' training clause and the DPA's limit on use outside the service sit side by side without a reconciling sentence (20 of 30). Dated deprecation notices in the changelog, no written notice policy (15 of 20). Sub-processors sit behind the trust centre, which we couldn't read without a browser. Regional status components for the US, EU, APAC and Australia (10 of 20).

MiniMax Speech (T2A) 65

Closed API with clear terms under Singapore law naming Nanonoble Pte. Ltd., and MIT MCP servers (15 of 30). Terms and privacy policy agree that inputs may be used to improve services and that data sits in a United States data centre, with no retention period, as on minimax-voice-cloning (8 of 30). The API release notes carry a dated legacy notice of 20 June 2025 for the old text-to-voice API with service continuing, and older speech models stay accepted, with no written policy or notice period (15 of 20). Data location stated as the United States and an EU representative named, third parties only by category (10 of 20). Total 48.

Cartesia Sonic TTS API + MCP 86

OpenAPI files for the latest and each dated API version, plus AsyncAPI files for the WebSocket, are listed in llms.txt (25). llms.txt and Markdown pages (10). A page compares the bytes, SSE and WebSocket endpoints and says which to use for what, and model pages explain dated snapshots (15 of 20). Typed request bodies with enums for container, encoding and sample rate, and a 0.6 to 1.5 range on speed (13 of 15). Examples in curl and both SDKs, but no error responses documented for the TTS endpoints, only SDK exception classes (8 of 15). Dated Cartesia-Version header, dated model snapshots that never change, and a monthly changelog (15).

MiniMax Speech (T2A) 81

OpenAPI 3.1 for the sync and async routes and AsyncAPI files for the WebSocket and bidirectional sockets (25). llms.txt and a Markdown copy of every page (10). The text field says when to stream and how to mark pauses, and guides separate sync, WebSocket and async use (15 of 20). Enums for model and audio settings, with model and text required (13 of 15). Examples throughout and the shared table of error codes, but the OpenAPI file documents only a 200 response (10 of 15). Versioned /v1 paths. The API release notes stop at 28 October 2025, and the last T2A entry is 23 September 2025 (8 of 15). Total 81.