Under the hood
ToolSearch now filters the tool pool per agent and session betas before running its search.
ToolSearchTool now takes agentId and stickyBetas from context and filters the tool pool through a new per-agent filter before running keyword/select search, rather than searching the raw tool list directly.
Names in the bundleToolSearch
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.
Added since
A small documentation edit on Create custom subagents touched a line naming ToolSearch after this was published.
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
Confirmed since
Anthropic's documentation has since written up ToolSearch, on Batches.
- `ToolSearchToolResultBlockParam object`api/messages/batches see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up ToolSearch, on Batches.