Exa API + MCP vs Tavily API + MCP

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.

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.

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. Add ?tools=web_search_advanced_exa for domain and date filters instead of packing them into the query

Tavily API + MCP

1. Try X-Tavily-Access-Mode: keyless first for search and extract, then switch to a key or x402 when the limit hits
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}