registerTool with zod raw shape: refine/superRefine/transform are silently dropped from validation

[qiyueqiu]

Problem

registerTool(name, { inputSchema: <zod object> }) validates against the raw shape only; refine / superRefine / transform constraints never run. A payload rejected by schema.safeParse passes the server gate — a fail-open validation gap for tools whose security-critical constraints are expressed via refine/superRefine.

Suggestion

1. Run the full ZodObject parse (the authoritative safeParse) in the tool wrapper, or
2. Document the limitation loudly in the registerTool signature so integrators know refine-level constraints require their own wrapper.

Context

Observed on @modelcontextprotocol/sdk 1.30.0. Our mitigation: the tool wrapper runs an authoritative safeParse itself before delegating (regression-tested).

[jstar0]

I would like to investigate this as a focused validation-correctness fix on main/v2. I will trace the registerTool wrapper and its Zod conversion path, verify how refine/superRefine/transform behave at the actual request boundary, and add a regression that proves constrained inputs cannot bypass the authoritative schema. I will keep the public API and validation semantics as narrow as possible and report whether v1.x can share the fix.