Problem

projectRuntimeToolInputSchema() currently serializes runtime tool schemas through JSON.stringify() before validating the projected JSON value. JavaScript non-finite numbers are not JSON values, but JSON.stringify() silently converts them to null.

A schema such as:

projectRuntimeToolInputSchema({
  type: object,
  properties: {
    amount: { type: number, maximum: Number.POSITIVE_INFINITY },
    score: { type: number, default: Number.NaN },
  },
});

can therefore be projected as if the schema explicitly contained null limits/defaults, while reporting no violation.

Expected behavior

Non-finite numeric schema values should be treated as non-JSON-serializable and should produce a schema projection violation instead of being silently changed to null.

Impact

The shared projection path feeds OpenAI and Anthropic tool schema construction. A bad tool schema should be quarantined with a clear diagnostic while healthy sibling tools remain available.