Crawling makes sense (automated traffic) but this isn’t automated, it’s user initiated. Search indexing makes sense (this isn’t that). Training makes sense (this isn’t that).
It should have a honest user agent so server can filter, for sure.
If I’m allowed ‘git clone X && grep -r’ against a service, why can’t I do the same with MCP.
But should the author be able to opt out of a tool used for manually initiated queries? I can’t say “don’t use grep” on my repo.