Is there a reason the _meta fields are not prefixed?

[mkouba]

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Your Question

If I understand it correctly, a tool _meta may contain a key ui (with no prefix, see https://modelcontextprotocol.io/specification/2025-11-25/basic/index#_meta) and the value is an object that contains for example property resourceUri.

Is there a reason a reserved prefix (e.g. mcp) is not used? That would help to resolve ambiguities and collisions. So instead of _meta["ui"].resourceUri the apps would use _meta["mcp/ui"].resourceUri.