> "As part of the task, they were supposed to have the ability to read the internet but not to write on it."

There's no such thing as only having "read" access with HTTP. If the website saves part of the GET URL as input in any way - like through standard "?input=my+text" params - then the AI has the ability to "write". The way servers use the request URL is completely arbitrary - the params could be "/input/my%20text" or entirely encoded in some way - there's no way to completely prevent this.