Reject model IDs unsafe for headers and clarify supported capabilities

README.md

@@ -3,9 +3,9 @@
 Use [uniGPT](https://unigpt.uni-graz.at), the University of Graz's AI
 assistant, inside the [pi](https://pi.dev) coding agent.
 
-Once set up, every model your uniGPT account offers appears in pi's model
-picker, including GPT-4o, GPT-4.1, and the GPT-5 and GPT-6 families. Tools,
-streaming responses, and image input all work.
+Models exposed by your uniGPT API key appear in pi's model picker.
+Streaming and tool calls are supported; recognized vision models also
+support image input.
 
 ## What you need