{"version":"2.1.273","anchor":"tool-call-duration-now-attached-to-posttooluse-produced-mess","canonical_anchor":"assistant-tool-result-messages-now-carry-a-toolduration-fiel","heading":"Tool calls now report their duration","tier":"internal","area":"Hooks","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.273\/e\/tool-call-duration-now-attached-to-posttooluse-produced-mess","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.273","markdown":"### Tool calls now report their duration\n\nAssistant messages for tool results now include how long the tool call took (toolDuration)\n\n**What** After a tool call completes (including after PostToolUse hooks run), the resulting message now carries a `toolDuration` field with the tool's name and how long it took, in milliseconds. These per-call durations feed into a `toolDurations` array that gets aggregated elsewhere, such as in request payloads and session statistics.\n\n**Why** This gives visibility into how long individual tool calls take, supporting reporting and aggregation of tool performance across a session.\n\n- Area: Hooks\n- Tier: Under the hood\n- Useful: 1\/5\n- Signal: 1\/5"}