toolInvocationToken
An opaque object that ties a tool invocation to a chat request from a chat participant.
The only way to get a valid tool invocation token is using the provided toolInvocationToken from a chat request. In that case, a progress bar will be automatically shown for the tool invocation in the chat response view, and if the tool requires user confirmation, it will show up inline in the chat view.
If the tool is being invoked outside of a chat request, undefined should be passed instead, and no special UI except for confirmations will be shown.
Note that a tool that invokes another tool during its invocation, can pass along the toolInvocationToken that it received.