Unclear It is not clear whether the new error is returned to the model for everyone or only recorded in some cases.
What
Some MCP tools are deferred: they are listed but not loaded until the model fetches them with the tool search tool. Calling a deferred tool before it is loaded already failed with an input error. For browser, computer use and simulator tools, the error now says that the tool was not loaded when it was called and tells the model to load it first. Claude Code also records when this check fails.
Why
The model gets a clear signal about what went wrong and what to do next, which changes how its early calls to these tools fail and recover.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
It is not clear whether the new error is returned to the model for everyone or only recorded in some cases.