The SDK wraps a raw shape in a plain z.object, which strips an undeclared
key and runs the handler as if nothing was wrong: an assistant that wrote
stopType for stop_type was told the place was updated while nothing had
changed. The registry registers every shape as z.strictObject, so the call
answers "Unrecognized key" and tools/list advertises additionalProperties
false. The nested objects a tool takes, authored inline or spread from a
shared schema (legs, stops, links, transit places), are strict at this
boundary for the same reason; the shared schemas themselves stay open for
REST. A whole Zod schema, the way a plugin's manifest-built tool arrives,
passes through as its author wrote it.
Prompt arguments cross the wire as strings, but the three trip prompts
declared tripId as z.number(), so every prompts/get failed with -32602
"expected number, received string", MCP Inspector included. The id is now
parsed from the string through a shared tripIdPromptArg (still an integer
in the safe range), PromptOptions only admits string-input schemas so the
mistake cannot come back unnoticed, and a prompt declared with an empty
argsSchema no longer demands an empty arguments object from the client.
The prompt tests run through a real in-memory MCP client instead of
calling the callbacks directly.
Maurice