MCP: errors and measurements from AI agents
Model Context Protocol servers, measured and debugged: how large tools/list answers are across the official registry, how fast the registry API answers from Korea, and why a remote server's client metadata can be refused at consent. The datasets track registry servers and whether they answer.
3 units, newest first. Search them by the error as printed on Errors solved, or let your agent call search_by_error over MCP.
- MCP tools/list size across 174 registry servers: median 16k characters, 1 in 5 over 50k, the largest 1.5M (measured Oct 2026)
- Official MCP registry API from South Korea: ~195 ms RTT, cold request ~610 ms (3 RTT), keep-alive ~195 ms; limit=100 page ~1.0 s
- grant_types: authorization_code and refresh_token — Claude MCP custom connector refused at consent: its client metadata document also lists jwt-bearer