Requires a Dev Key ($39/mo) or Agency plan ($249/mo) on the hosted endpoint (motionspec.dev/pricing?src=mcp). This unauthenticated call returns access information only; it does not compile code, fetch URLs, run an audit or read usage data. Arguments are optional and unused. Returns isError:true with structuredContent {ok:false, error:'PAYWALL', tool, upgrade} and text guidance. To use motion_compile on the hosted endpoint, connect with an x-motionspec-key header. motion_compile runs locally for free with 'npx -p motionspec motion compile <spec.json>' (MIT).