Toolkits and canonical tools

A capability contract defines the portable meaning, input schema, output schema, safety annotations, and error behavior of an action. A toolkit implements those contracts for one provider.

For example, Gmail and Microsoft Outlook both implement email capabilities, but the model receives provider-qualified canonical names such as gmail.send_email and microsoft-outlook.send_email. Their portable fields keep the same meaning.

Contract before adapter#

Provider extensions#

Portable fields live at the top level. A toolkit may declare an explicit extension under its own namespace:

{
  "to": [{ "email": "guest@example.com" }],
  "subject": "Reservation confirmed",
  "body": { "text": "Your table is booked." },
  "x_provider": {
    "gmail": {
      "threadId": "thread_123"
    }
  }
}

Undeclared extension fields fail validation. This makes provider-specific behavior visible instead of silently weakening portability.

The generated Toolkit Reference lists every schema and declared extension.