I have one Tavily key on the free tier, 1,000 credits a month, reset on the 1st. Claude Code, Codex and Hermes all use that same key. When sessions run in parallel they drain one pool, and none of them sees what the others spent. On 2026-09-15 I measured it: 786 credits across 113 calls. So a single Tavily MCP call costs several credits, not 1. The heavy calls are worse. A crawl is 100+ credits, and tavily_research can be anything from 4 to 250. So research is never called now without flagging the cost first. On 09-19 I moved whole-site and follow-links jobs to Scrapling, free and local. Tavily crawl/map is only the fallback now. The order is WebSearch, then Google in the browser pane, then Scrapling, then Tavily. One task gets at most ~3 Tavily escalations before it stops and says so. Scrapling has its limits too, measured the same day. Cloudflare-walled pages only pass with real_chrome=True, the bundled Chromium fails there. DataDome on ImmoScout24 stays closed. What I take from it: pick the tool that's most effective first, and the free one only when it's a tie. And measure what a metered call really costs before you budget around it. If you share one metered API key across several agents or tools, how do you track and cap what each of them spends?