What
The data passed to a PostToolUse hook now includes an optional duration_ms, the tool's own execution time. It excludes time spent on permission prompts and on other hooks, so it reflects the tool rather than the wait around it.
Evidence
Tool execution time in milliseconds. Excludes permission-prompt and hook time.
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
Names in the bundleduration_ms
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 Customize your status line touched a line naming duration_ms after this was published.
| `cost.total_duration_ms` | Total wall-clock time the session has been running, in milliseconds. Accumulates across resumes and doesn't include time while the session isn't running |statusline see the edit
Confirmed since
Anthropic's documentation has since written up duration_ms, on Monitoring.
| `interaction.duration_ms` | Wall-clock duration of the turn | |monitoring-usage 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 duration_ms, on Monitoring.