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Sweep 22 Oct 2026 · 21:04Z Build v2.1.309 528 read Stable v2.1.308 Latest v2.1.309 Next v2.1.309 Feeds RSS JSON llms.txt llms-full.txt Unofficial
HomeDocsClaude Developer Platform 22 Oct 2026
One change · api

Or, for Claude Mythos 5.1, which offers the same capabilities to verified organizations: changedmodels/fable-5-1/migration-guide

Nearest release: v2.1.309, published under an hour before this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.

Recorded here
Lines+6added
Lines−8removed
From line 794 where the diff opens
First seen 1 Sep 2026 this site's first read of the page
Recorded edits28to this page, all time

The whole hunk

from line 794, old and new numbered
/
lines
from line 794
794794 // The application requires a help center lookup before any policy
795795 // answer. Appending the requirement as a system message leaves the
796796 // earlier turns unchanged.
797 {
798 Role: anthropic.MessageParamRoleSystem,
799 Content: []anthropic.ContentBlockParamUnion{
800 anthropic.NewTextBlock("Tool-use requirement for the current turn: the application requires a call to the search_help_center tool in your response to the user's latest message. Begin your response with the search_help_center tool call. Do not reply with text only."),
797 {OfSystem: &anthropic.SystemMessageParam{
798 Content: []anthropic.TextBlockParam{
799 {Text: "Tool-use requirement for the current turn: the application requires a call to the search_help_center tool in your response to the user's latest message. Begin your response with the search_help_center tool call. Do not reply with text only."},
801800 },
802 },
801 }},
803802 },
804803 })
805804 if err != nil {
from line 1372
13731372 },
13741373 Messages: []anthropic.BetaMessageParam{
13751374 anthropic.NewBetaUserMessage(anthropic.NewBetaTextBlock("Plan a migration from SQLite to PostgreSQL in three short steps.")),
1376 {
1377 Role: anthropic.BetaMessageParamRoleAssistant,
1375 {OfAssistant: &anthropic.BetaAssistantMessageParam{
13781376 Content: []anthropic.BetaContentBlockParamUnion{anthropic.NewBetaTextBlock("1. Export the SQLite data. 2. Create the PostgreSQL schema. 3. Import the data and verify row counts.")},
1379 },
1377 }},
13801378 // Effort-only system message: the new level takes effect from the next user turn.
13811379 anthropic.NewBetaSystemMessage(anthropic.BetaSystemMessageOutputConfigParam{
13821380 Effort: anthropic.BetaSystemMessageOutputConfigEffortLow,
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