[BUG] .yaml type description forbids fields starting with underscore `_`

[bgaidioz]

Describe the Bug

I decided to name certain metadata fields with underscores in front (e.g. __url or __type) because I've seen the LLM confusing them with regular object members that can be queried/filtered, etc. After they got named with __ in front, they looked "internal" and weren't used for filtering or projection.

But when documenting that in .yml, I hit the error by Pydantic: "Fields must not use names with leading underscores;". Because we internally turn the .yml into Pydantic models.

To Reproduce

Declare a tool that returns an object which has a field starting with _.

Expected Behavior

It's working as if nothing.

Environment

Configuration

          properties:
            objid:
              type: string
              description: Object ID (for tool chaining/internal reference only).
            __object_type:
              type: string
              description: object type for the returned object (metadata).
              examples: ["Project", "Invoice"]
            __info:
              type: string
              description: Object metadata (string representation).
            __url:
              type: string
              format: uri
              description: Direct link to the object in Vertec.

Error Output

Paste the full error output here

Additional Context

I got around by naming members meta_url, meta_type. Which I imagine will also work.

That said, imagine a user is running an existing REST API from the tool, and that API returns a JSON with underscores like that, it would be silly that the person has to rename all these fields because we use pydantic models (it's an internal detail).