Arcmira vs Tavily API + MCP

Arcmira

Four code-mode tools over a documented v1 API, OAuth 2.1 with four scopes, a read-only sign-up key from two API calls and no card, and a 1,000-credit free month. No status page, SLA or security.txt, breaking v1 changes shipped in October with same-day notice, the server is at 0.10.7, and the index covers the shows Arcmira transcribes.

Tavily API + MCP

Keyless search and extract, plus a free 1,000 credits a month with no card. x402 covers advanced search only, not extract, map, crawl or research.

Arcmira

1. Call arcmira_describe once per session and write one program per question for arcmira_execute_read; return only the fields the answer needs, since output is cut at 12,000 characters and 3,000 per string.
2. Resolve names with arcmira.resolve (free) before any about, by, entity_ids or channel filter; a name in a filter fails with id_required. Plain keyword search needs no resolver call.
3. Check arcmira.status() or GET /v1/me for the plan, scopes and usage.credits.available before metered reads; on Free, media newer than 30 days and pages past the first fail with freshness_requires_paid and pagination_gated.
4. A Premium read of an untranscribed video starts a transcription that uses credits (300 per started 15 minutes) and may return pending; read the same video again later, which is never charged twice, and send retry: true only when the user asks.
5. Over HTTP send Authorization: Bearer arc_sk_..., an Idempotency-Key on every POST and PATCH, honour Retry-After on 429, and switch on error.code, following unlock.url on 402 and 403 rather than re-authenticating.
6. Use arcmira_execute_write only after listing the user's monitors; it creates, follows and pauses but never deletes, and a connection made before server 0.9.0 answers insufficient_scope until reconnected.

Tavily API + MCP

1. Try X-Tavily-Access-Mode: keyless first for search and extract. Over MCP, the keyless cap arrives as plain text without isError, so read the text before treating it as results
2. Send the key in Authorization: Bearer, not ?tavilyApiKey= in the MCP URL
3. On 429, wait for Retry-After. A 432 or 433 means a spend limit, and retrying won't help
4. Run /map before /crawl to bound the crawl, since crawl is billed as map plus extract
5. Research is async and runs 4 to 250 credits. Create the task, then poll /research/{request_id}