A new preprint analyzed 177,436 MCP tools deployed between November 2024 and February 2026. The headline number: action tools — tools that directly modify external environments — went from 27% to 65% of total MCP tool usage in 16 months.
That's a 2.4x increase in the share of tools that do things to the world, not just read from it.
The study is provides. Every agent action passes through an approval gate. Every approved action is recorded in an Ed25519-signed, hash-chained audit log. The trail leads from tool call to agent to human owner.
At 27% action tools, this was a nice-to-have. At 65%, it's infrastructure.
Data source: Stein, M. "How are AI Agents Used? Evidence From 177,000 MCP Tools." arXiv:2603.23802, March 2026. 177,436 tools analyzed across 16 months (November 2024 – February 2026).
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