AssemblyAI Voice Agent API vs fone.me

AssemblyAI Voice Agent API 83

An AsyncAPI 3.0 file describes the socket and an OpenAPI 3.0.3 file the token endpoint. No description file was found for the agents, sessions and webhook REST endpoints, and the AsyncAPI file lacks language_codes, voice_focus, transcript.agent.delta and is_error, which the docs added on 23 July 2026 (19 of 25). llms.txt, a Markdown copy of each page and a docs MCP server (10). Operations and fields say what they are for and when to use them, such as when to choose hold over interactive execution (17 of 20). Enums, ranges and defaults on audio encoding, turn detection and timeouts. Tool parameters are a JSON Schema the server does not validate at session.update (12 of 15). Examples in cURL, Python and JavaScript, and tables of session error codes with close codes (13 of 15). A dated public changelog tagged by product and a /v1 path, with no written versioning policy found (12 of 15).

fone.me 31

MCP reading, since the MCP server is what an outside agent calls. No tool arguments or input schemas are published in llms.txt, the guide pages or the GitHub README, and robots.txt disallows /mcp, so no session was opened and tools/list was not read. Per-link A2A agent cards are machine-readable JSON (protocol 0.3.0, JSONRPC, input and output modes, skills with examples) and server.json names the remote, but neither types the MCP tools (8 of 25). llms.txt is a real document for agents covering the MCP server, A2A, the search API and the widget (10). Each tool has a one-line purpose in llms.txt and the README, and the how-it-works page states what the agent will and won't do; nothing says when not to use a tool (6 of 20). No typed inputs, enums, constraints or required fields published (0 of 15). Example prompts in the README, per-skill examples in agent cards and widget code for eight site builders; no error response is documented (4 of 15). server.json and the agent cards carry version 1.0.0 and the cards a protocol version; no changelog (3 of 15). 8+10+6+0+4+3 = 31.

AssemblyAI Voice Agent API 65

Scored with the hosted lines. Statuspage at status.assemblyai.com with component history, read from history.atom on 2 November, but its components are the Asynchronous API, Streaming API and LLM Gateway and none is the Voice Agent API (15 of 20). Thirteen incidents from 4 August to 2 November 2026 (14 August to 28 October) and none names the Voice Agent API. Four touch the realtime speech-to-text it runs on, all partial. New EU streaming sessions were refused for 12 minutes on 19 August, with 30 minutes of added latency on the US endpoint on 25 August, two hours of rejected Universal-3.6 Pro Realtime sessions on the US endpoint on 6 October (the EU endpoint unaffected), and some Real-time sessions failing with 502 after a temporary-token change on 28 October until it was rolled back. Whether agent sessions were affected isn't stated. Read as minor incidents touching the product, as assemblyai-stt reads the same feed (20, was 15, which isn't a checklist value). A per-account concurrent-session limit is enforced and no figure is published for it (0 of 15). The events reference (re-read on 2 November) names at_capacity, concurrency_exceeded and internal_error as the only retryable codes and says to reconnect with backoff, and sessions resume for 30 seconds. Webhooks carry a stable event_id. No idempotency key on POST /v1/agents (10 of 15). A Service Level Agreement of 99.9 per cent a month with credits, written against an Order Form, per the 9 October check (10). No beta label on the Voice Agent pages (10). 15+20+0+10+10+10 = 65.

fone.me 15

Hosted reading, for the MCP server and A2A endpoints and the service behind them. No status page is linked from llms.txt, the home page or any guide page read, and https://www.fone.me/status failed to load (0). No readable incident history, so the floor (5). No request rate limit for the MCP server, the search API or A2A is published; the only limits are on the agent's own outbound calls (8 am to 9 pm in the callee's time zone, 'limited per day' with no number), which are not request limits (0 of 15). No 429, overload or retry guidance and no idempotency key for message_agent or message/send (0 of 15). No SLA (0). Nothing on the MCP server, the agent cards or llms.txt is marked beta or preview, and the MCP repository's server.json is version 1.0.0 (10). 0+5+0+0+0+10 = 15.

AssemblyAI Voice Agent API 0

No x402, MPP or L402 (0 of 40). On 2 November the pricing page lists speech-to-text, dictation, text-to-speech and LLM Gateway prices but no Voice Agent API price, and the billing docs have no Voice Agent section. The $4.50 an hour rate the 9 October check read on both is no longer published, and no other price page was found (0, was 20). The billing docs now say new accounts' $50 of credit applies to pre-recorded and real-time speech-to-text, Speech Understanding and Guardrails, without naming the Voice Agent API, where on 9 October they said it was covered (0, was 20). A person has to sign up in a browser to get the first key, and no key-creation API was found (0). 0+0+0+0 = 0.

fone.me 50

No x402, MPP or L402 on any page read (0). Premium is $9.99 a month on llms.txt and the Smith.ai comparison page, with no minute allowance or per-call price (10 of 20). The MCP server, search API and A2A endpoints are free with no account, and the agent, first link and chat button are free for owners; no page mentions a card for any of these (20). An outside agent needs no sign-up, key or payment to find and message an agent (20). 0+10+20+20 = 50.

AssemblyAI Voice Agent API 68

A closed service with a clear service agreement. The starter repositories have no licence file (15 of 30). The Terms of Service grant a licence to train on Customer Data by default, the opt-out needs a paid plan, and the retention page gives periods for streaming, sync, dictation, asynchronous and LLM Gateway data but none for Voice Agent sessions, which are recorded and stored. A DPA is published and the privacy policy states Data Privacy Framework certification (14 of 30). The changelog dates deprecations ahead of time, such as the 11 July 2026 notice of a change on 7 August, and the terms promise reasonable prior notice of major changes. No written deprecation policy was found (12 of 20). The subprocessor list at /legal/subprocessors redirects to a Vanta trust centre whose robots.txt disallows every path, so it is unread. US and EU endpoints are mentioned, with no EU host named for the Voice Agent API in the pages read (10 of 20). 15+14+12+10 = 51.

fone.me 23

Closed service. Terms of service exist at /terms but draw by script, so their content, governing law and the company they name are unchecked; no company, address or country of incorporation appears on any page read, llms.txt says San Francisco, and the MCP repository has no licence (5 of 30). Data handling was read only from guide pages, which say only the owner sees their calls and messages, calls are transcribed and callers told so, and private categories are withheld. The privacy policy and data-deletion page draw by script, so no retention period, recording statement, DPA or AI-training statement was read (8 of 30). No deprecation policy or dated notices (0). No subprocessors, telephony, model or hosting providers or data locations are named on any page read; the demo agent card's icon is served from Cloudinary (0 of 20). 5+8+0+0 = 13.

AssemblyAI Voice Agent API 72

Scored as an API. Events are small typed JSON, HTTP tool responses are capped at 8 KiB before they reach the model, and the session list leaves artefacts out (18 of 25). GET /v1/sessions pages by cursor with limit from 1 to 200 and filters on status and agent_id (18 of 20). Errors carry code, message and sometimes param, and REST validation errors name the field (17 of 20). No idempotency keys on REST writes. Sessions resume within 30 seconds, webhooks dedupe on event_id, and hold mode silences the agent during long tools (10 of 20). An agent needs three fields (name, system_prompt, voice). The official Python and Node SDKs have no Voice Agent client, so callers write JSON over a socket or start from the two starter repositories (9 of 15).

fone.me 29

MCP reading. Four tools named in llms.txt, a small set, but their definitions were not read, so short of full marks (18 of 25). find_agents searches by what someone does and the search API takes a query; no limit, paging or output-size controls are documented (3 of 20). No error codes or messages documented for the MCP server, the search API or A2A (0 of 20). No readOnlyHint or destructiveHint seen and no idempotency key; the three lookups are read-only by name and description, while message_agent writes to a real person's inbox and continues the conversation across calls (2 of 20). No credentials, no configuration beyond the URL, and few stated inputs; no SDK in any language (6 of 15). 18+3+0+2+6 = 29.

AssemblyAI Voice Agent API 64

The last changelog entry tagged Voice Agent API is Pre-Connect Requests on 16 September 2026 (47 days before 2 November), which the 9 October check didn't count (20). Five tagged entries since 4 August (18 August, three on 26 August, 16 September) (20). A public changelog that records fixes, a support address and a Discord link we did not test (11 of 15 for a closed service). The Python and Node SDKs still have no Voice Agent client (Node 4.42.0 of 26 October added text-to-speech clients), and the two starter repositories were last changed on 16 August 2026 (8 of 15). The starters need no dependencies and have no licence file, tests or CI (5 of 10). 20+20+11+8+5 = 64.

fone.me 23

Closed service. The newest dated change to the agent surface found is the MCP repository github.com/spearisa/fone-me-mcp, created 5 October 2026 with server.json version 1.0.0, 31 days ago (20). The comparison page marked 'Checked October 28, 2026' and the profile lastmods in the sitemap are content, not releases. No changelog, release notes or three dated changes in 90 days (0 of 20). The support page and FAQ draw by script and no support email, forum or community channel was found; responsiveness unchecked (3 of 15). server.json names the server me.fone.www/agents, a namespace that needs proof of the domain, but the official MCP registry could not be read, so presence is scored absent (0 of 15). No package, public code or CI (0 of 10). 20+0+3+0+0 = 23.