firstContentMs
A Claude Code settings key, read out of the shipped bundle. No mined inventory carries it: everything below comes from what this site has written about it.
Claude Code now records how long it took to get the first bit of a response back, as ttft_ms in telemetry
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.268.
In the changelogs
2Releases whose published page names firstContentMs.
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v2.1.268
api_request telemetry gains a ttft_ms field and firstContentMs tracking
Claude Code now records how long it took to get the first bit of a response back, as ttft_ms in telemetry
found in this entry's text
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v2.1.268
tengu_api_success gains firstContentMs, clientRequestId, user_message_uuid
API success telemetry now records time-to-first-content, a client request id, and the user message's UUID
found in this entry's text
First cited
1The earliest release whose published evidence quoted firstContentMs was v2.1.268, 10 Sep 2026. That is the oldest release this project wrote about it, so it is a floor on the name's age and not the release that introduced it. It is not a presence reading: which builds carried the name is the table below.
Presence across releases
0The miner has never read a build containing this name. It is here because a changelog entry of ours names it, which is evidence that it existed and not evidence of which releases carried it. The inventory starts at v2.1.138 and everything older than that was never mined.
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the settings key does. All settings keys.