What
Tools that come from MCP servers (add-ons that give Claude extra tools) have names that start with a prefix naming the server. Sometimes Claude calls a browser tool by its bare name, such as read_page, find, form_input, computer or navigate. When exactly one loaded tool ends with that name, has a known prefix and accepts the arguments given, the error message now tells Claude which tool to call instead.
If that tool is deferred (loaded only on demand), the message also tells Claude to load it first with ToolSearch using select:. Before, the only hint of this kind was about names that differed in upper or lower case.
Why
Claude gets back on track faster after guessing a browser tool's name, instead of trying again blind.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
Which server prefixes count as known is not settled.