Tool descriptions are load-bearing too: the anti-purpose pattern in MCP

A few days ago I posted Schema descriptions are load-bearing: why missing parameter descriptions break MCP clients . The argument: every parameter without a description is a load-bearing element silently absent from the schema, and agents fail in ways that look like model problems but are actually contract problems. The post got a comment from @mickyarun that's worth its own essay: The "load-bearing" framing is the right shape — the same observation applies one level up at the tool level. Most M