Arcmira vs Exa 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.

Exa API + MCP

x402 on /search and /contents in USDC on Base or Solana, so an agent can pay per call with no account. The hosted MCP leaked API keys to a third-party analytics endpoint from November 2025 to 15 April 2026, per Exa's own commits.

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.

Exa API + MCP

1. Send the key as x-api-key or a Bearer header, never ?exaApiKey= in the MCP URL
2. Ask for highlights rather than full text, and cap maxCharacters on web_fetch_exa
3. Request only the results you'll read. More than 10 costs extra, and x402 calls stop at 10
4. On 429, honour Retry-After. The QPS limit is shared by every key on the team
5. Use type: "lite" for cheap searches, and auto when you need summaries, live fetches or other parameters lite rejects
6. Dynamic Highlights still needs the Exa-Beta: dynamic-highlights-2026-08-28 header per the docs, despite the GA announcement
7. Set budget.maxCostDollars on agent_run, which a keyed MCP connection may now expose by default