The NotebookEdit tool's permission-checking, input-validation, and execution logic have been moved into a per-call factory function, matching the pattern already used by other tools that are scoped to a specific agent or session. As part of this, NotebookEdit's execution step now throws an error if it can't find the message that originally issued the call.
This is an internal restructuring that brings NotebookEdit in line with how other tools are built, and it tightens the tool so it fails loudly if it ever loses track of the message that triggered it, rather than proceeding with missing context.
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
The second filter applies to subagents running in the background. Apart from `Agent` and `ExitPlanMode`, which follow the first filter's conditions wherever the subagent runs, a background subagent keeps every MCP tool but only these built…sub-agents see the edit
The second filter applies to subagents running in the background. Apart from `Agent` and `ExitPlanMode`, which follow the first filter's conditions wherever the subagent runs, a background subagent keeps every MCP tool but only these built…sub-agents see the edit
Anthropic's documentation has since written up NotebookEdit, on Create custom subagents.