tengu_malformed_tool_use_clean_retry
A Claude Code feature flag, read out of the shipped bundle.
It was in the build from v2.1.174 and was gone by v2.1.251.
Default false. When a response stops with tool_use but no tool call could be parsed, Claude Code retries once; with this flag on, the malformed assistant messages are tombstoned and dropped from the retry and the nudge reads The previous response failed to produce a valid tool call. Please retry the tool call now. With it off, the malformed messages stay in the history and the nudge is Your tool call was malformed and could not be parsed. Please retry.
Not Anthropic's. Written by Claude Opus 5.5 from reading the v2.1.250 bundle, and it can be wrong.
First seen v2.1.174 11 Jun 2026
Last seen v2.1.250 27 Aug 2026, gone by v2.1.251
Builds68 / 149on this box, as of v2.1.308
Written about — no changelog entry names it
v2.1.174in the build not in the build never minedv2.1.308
In the changelogs
0
No changelog entry here has ever named it. That is a statement about what has been written, not about the name: it has been in the build since v2.1.174 without anybody writing a line about it.
Gate readings
0
No release here has a gate table behind it for this flag. Most published releases have none at all: the readings exist only for versions the pipeline captured flag state on.
Flag server, over time
12
| Read as | Reading | From | Until | Version installed |
|---|
| anonymous |
off |
2026-10-17T05:30:04Z |
2026-10-22T17:35:05Z |
v2.1.302 to v2.1.308 |
| this account |
off |
2026-09-10T21:47:12Z |
2026-10-22T17:35:05Z |
v2.1.268 to v2.1.308 |
| anonymous |
no longer carried |
2026-10-17T05:25:57Z |
2026-10-17T05:25:57Z |
v2.1.302 |
| anonymous |
off |
2026-08-19T04:25:04Z |
2026-10-17T05:10:04Z |
v2.1.233 to v2.1.302 |
| this account |
no longer carried |
2026-09-10T21:46:45Z |
2026-09-10T21:46:45Z |
v2.1.268 |
| this account |
off |
2026-09-08T20:36:15Z |
2026-09-10T17:40:05Z |
v2.1.263 to v2.1.267 |
| this account |
no longer carried |
2026-09-08T20:34:58Z |
2026-09-08T20:34:58Z |
v2.1.265 |
| this account |
off |
2026-09-06T02:40:05Z |
2026-09-08T18:45:05Z |
v2.1.261 to v2.1.263 |
| this account |
no longer carried |
2026-09-06T02:36:19Z |
2026-09-06T02:36:19Z |
v2.1.263 |
| this account |
off |
2026-08-14T22:10:05Z |
2026-09-06T01:55:04Z |
v2.1.232 to v2.1.261 |
| anonymous |
no longer carried |
2026-08-19T04:20:14Z |
2026-08-19T04:20:14Z |
v2.1.233 |
| anonymous |
off |
2026-08-14T22:10:05Z |
2026-08-19T03:45:04Z |
v2.1.232 to v2.1.233 |
One row per unbroken stretch of one reading, newest first, from snapshots taken every twenty-five minutes or so. No longer carried is not off: it means the flag server stopped returning the gate at all, which is what a retired experiment looks like. The version column is what was installed when the reading was taken, not what caused it.
First cited
0
No release's published evidence quotes this name. The ledger indexes the Evidence lines of every changelog on this site, so this says nobody here has ever quoted it; it says nothing about how old the name is.
Presence across releases
2
BuildsHow manyDatesReading
v2.1.174 – v2.1.25068 builds11 Jun 2026 → 27 Aug 2026 ◆in the build
v2.1.251 – v2.1.30849 builds28 Aug 2026 → 22 Oct 2026 ○not in the build
Build by build
117
One row per release since the first build this name was read out of. Absent means the build was read and the name was not in it, never mined means no bundle for that release was ever archived, and a declared type or a default is only ever what that release's own bundle stated.
BuildDateStateThe record behind it
v2.1.17411 Jun 2026·addedverdict: added · default bool:false
v2.1.17512 Jun 2026·presentverdict: present · default bool:false
v2.1.17612 Jun 2026·presentverdict: present · default bool:false
v2.1.17713 Jun 2026·presentverdict: present · default bool:false
v2.1.17815 Jun 2026·presentverdict: present · default bool:false
v2.1.17916 Jun 2026·presentverdict: present · default bool:false
v2.1.18117 Jun 2026·presentverdict: present · default bool:false
v2.1.18218 Jun 2026·presentverdict: present · default bool:false
v2.1.18319 Jun 2026·presentverdict: present · default bool:false
v2.1.18520 Jun 2026·presentverdict: present · default bool:false
v2.1.18622 Jun 2026·presentverdict: present · default bool:false
v2.1.18723 Jun 2026·presentverdict: present · default bool:false
v2.1.19024 Jun 2026·presentverdict: present · default bool:false
v2.1.19124 Jun 2026·presentverdict: present · default bool:false
v2.1.19325 Jun 2026·presentverdict: present · default bool:false
v2.1.19526 Jun 2026·presentverdict: present · default bool:false
v2.1.19629 Jun 2026·presentverdict: present · default bool:false
v2.1.19730 Jun 2026·presentverdict: present · default bool:false
v2.1.1981 Jul 2026·presentverdict: present · default bool:false
v2.1.1992 Jul 2026·presentverdict: present · default bool:false
v2.1.2003 Jul 2026·presentverdict: present · default bool:false
v2.1.2013 Jul 2026·presentverdict: present · default bool:false
v2.1.2026 Jul 2026·presentverdict: present · default bool:false
v2.1.2037 Jul 2026·presentverdict: present · default bool:false
v2.1.2048 Jul 2026·presentverdict: present · default bool:false
v2.1.2058 Jul 2026·presentverdict: present · default bool:false
v2.1.2069 Jul 2026·presentverdict: present · default bool:false
v2.1.20710 Jul 2026·presentverdict: present · default bool:false
v2.1.20813 Jul 2026·presentverdict: present · default bool:false
v2.1.20914 Jul 2026·presentverdict: present · default bool:false
v2.1.21014 Jul 2026·presentverdict: present · default bool:false
v2.1.21115 Jul 2026·presentverdict: present · default bool:false
v2.1.21216 Jul 2026·presentverdict: present · default bool:false
v2.1.21317 Jul 2026·presentverdict: present · default bool:false
v2.1.21418 Jul 2026·presentverdict: present · default bool:false
v2.1.21519 Jul 2026·presentverdict: present · default bool:false
v2.1.21620 Jul 2026·presentverdict: present · default bool:false
v2.1.21721 Jul 2026·presentverdict: present · default bool:false
v2.1.21822 Jul 2026·presentverdict: present · default bool:false
v2.1.21924 Jul 2026·presentverdict: present · default bool:false
v2.1.22024 Jul 2026·presentverdict: present · default bool:false
v2.1.2213 Aug 2026·presentverdict: present · default bool:false
v2.1.2224 Aug 2026·presentverdict: present · default bool:false
v2.1.2235 Aug 2026·presentverdict: present · default bool:false
v2.1.2247 Aug 2026·presentverdict: present · default bool:false
v2.1.2257 Aug 2026·presentverdict: present · default bool:false
v2.1.2268 Aug 2026·presentverdict: present · default bool:false
v2.1.22710 Aug 2026·presentverdict: present · default bool:false
v2.1.22811 Aug 2026·presentverdict: present · default bool:false
v2.1.22912 Aug 2026·presentverdict: present · default bool:false
v2.1.23113 Aug 2026·presentverdict: present · default bool:false
v2.1.23213 Aug 2026·presentverdict: present · default bool:false
v2.1.23314 Aug 2026·presentverdict: present · default bool:false
v2.1.23417 Aug 2026·presentverdict: present · default bool:false
v2.1.23518 Aug 2026·presentverdict: present · default bool:false
v2.1.23619 Aug 2026·presentverdict: present · default bool:false
v2.1.23719 Aug 2026·presentverdict: present · default bool:false
v2.1.23820 Aug 2026·presentverdict: present · default bool:false
v2.1.23921 Aug 2026·presentverdict: present · default bool:false
v2.1.24022 Aug 2026·presentverdict: present · default bool:false
v2.1.24122 Aug 2026·presentverdict: present · default bool:false
v2.1.24224 Aug 2026·presentverdict: present · default bool:false
v2.1.24324 Aug 2026·presentverdict: present · default bool:false
v2.1.24525 Aug 2026·presentverdict: present · default bool:false
v2.1.24625 Aug 2026·presentverdict: present · default bool:false
v2.1.24726 Aug 2026·presentverdict: present · default bool:false
v2.1.24827 Aug 2026·presentverdict: present · default bool:false
v2.1.25027 Aug 2026·presentverdict: present · default bool:false
v2.1.25128 Aug 2026·removedverdict: removed
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 feature flag does. All feature flags.
