MCP tools/list flattens anyOf array-or-null filter schema to scalar string

Minimal repro

Tool: flywheel_list_nodes

Input used by affected clients:

• owners: "me"

Expected canonical shape:

• owners: ["me"]

Observed behavior:

• Client flattens array-or-null schema (anyOf: [{"type":"array"}, {"type":"null"}]) into scalar-string guidance.
• Server rejects scalar with list validation (owners must be an array of strings).

Why this matters

This causes first-call tool failures and requires users/agents to manually discover array wrapping despite correct server schema.

Request

Please preserve array-or-null input schema shape in surfaced MCP tool manifests/instructions for list filters.