# Claude Code v2.1.257: system prompt > 2 added and 3 removed, of 78 lines, about 30 words, in the prompt all 1 arms receive. 1 of 24 tool descriptions changed. The appended system-reminder blocks moved: 2 lines added, 2 lines removed. Compared against v2.1.252. Web version: https://changelogs.core-directive.com/prompts/2.1.257?surface=compaction ## What this version holds - model strings captured: 1 - tool descriptions: 24 - compared against: v2.1.252 - system prompt edits: 1 - widest system prompt edit: +2/-3 lines - tool descriptions changed: 1 ## What moved ### System prompt (+2/-3 lines) This edit reached all 1 arms. ```diff @@ from line 52 @@ - OS Version: Linux 5.15.0-190-generic - You are powered by the model named Opus 5 (1M context). The exact model ID is claude-opus-5[1m]. - Assistant knowledge cutoff is May 2026. - - The most recent Claude models are the Claude 5 family and Haiku 4.5. Model IDs — Fable 5: 'claude-fable-5', Opus 5: 'claude-opus-5', Sonnet 5: 'claude-sonnet-5', Haiku 4.5: 'claude-haiku-4-5-20251001'. When building AI applications, default to the latest and most capable Claude models. + - The most recent Claude models are the Claude 5 family and Haiku 4.5. Model IDs — Fable 5.1: 'claude-fable-5-1', Opus 5: 'claude-opus-5', Sonnet 5: 'claude-sonnet-5', Haiku 4.5: 'claude-haiku-4-5-20251001'. When building AI applications, default to the latest and most capable Claude models. - Claude Code is available as a CLI in the terminal, desktop app (Mac/Windows), web app (claude.ai/code), and IDE extensions (VS Code, JetBrains). - Fast mode for Claude Code uses Claude Opus with faster output (it does not downgrade to a smaller model). It can be toggled with /fast and is available on Opus 5/4.8. ``` ```diff @@ from line 73 @@ A follow-up question about your earlier work is not, by itself, a signal that you got something wrong — answer what was asked. A statement that was accurate needs no correction: don't re-audit how you phrased it, how you verified it, or limits you already stated. When the user does point to a real error, correct it plainly as above. -Do not call the AgentTool unless the user requested it -Do not use workflows or deep-research unless the user requested it +Do not use the Agent tool, workflows, or deep-research unless the user, a CLAUDE.md file, or a skill asks for it 15000000 tokens left ``` ### Tool: WebSearch (+1/-1 lines) This edit reached all 1 arms. ```diff @@ from line 1 @@ Search the web. Returns result blocks with titles and URLs. US-only. -- The current month is August 2026 — use this when searching for recent information. +- The current month is September 2026 — use this when searching for recent information. - `allowed_domains` / `blocked_domains` filter results. - After answering from results, end with a "Sources:" list of the URLs you used as markdown links. ``` ## Tool descriptions - Agent: https://changelogs.core-directive.com/prompts/2.1.257/tools/Agent.txt?surface=compaction - AskUserQuestion: https://changelogs.core-directive.com/prompts/2.1.257/tools/AskUserQuestion.txt?surface=compaction - Bash: https://changelogs.core-directive.com/prompts/2.1.257/tools/Bash.txt?surface=compaction - CronCreate: https://changelogs.core-directive.com/prompts/2.1.257/tools/CronCreate.txt?surface=compaction - CronDelete: https://changelogs.core-directive.com/prompts/2.1.257/tools/CronDelete.txt?surface=compaction - CronList: https://changelogs.core-directive.com/prompts/2.1.257/tools/CronList.txt?surface=compaction - Edit: https://changelogs.core-directive.com/prompts/2.1.257/tools/Edit.txt?surface=compaction - EnterPlanMode: https://changelogs.core-directive.com/prompts/2.1.257/tools/EnterPlanMode.txt?surface=compaction - EnterWorktree: https://changelogs.core-directive.com/prompts/2.1.257/tools/EnterWorktree.txt?surface=compaction - ExitPlanMode: https://changelogs.core-directive.com/prompts/2.1.257/tools/ExitPlanMode.txt?surface=compaction - ExitWorktree: https://changelogs.core-directive.com/prompts/2.1.257/tools/ExitWorktree.txt?surface=compaction - ListAgents: https://changelogs.core-directive.com/prompts/2.1.257/tools/ListAgents.txt?surface=compaction - NotebookEdit: https://changelogs.core-directive.com/prompts/2.1.257/tools/NotebookEdit.txt?surface=compaction - Read: https://changelogs.core-directive.com/prompts/2.1.257/tools/Read.txt?surface=compaction - ReportFindings: https://changelogs.core-directive.com/prompts/2.1.257/tools/ReportFindings.txt?surface=compaction - ScheduleWakeup: https://changelogs.core-directive.com/prompts/2.1.257/tools/ScheduleWakeup.txt?surface=compaction - SendMessage: https://changelogs.core-directive.com/prompts/2.1.257/tools/SendMessage.txt?surface=compaction - Skill: https://changelogs.core-directive.com/prompts/2.1.257/tools/Skill.txt?surface=compaction - TaskOutput: https://changelogs.core-directive.com/prompts/2.1.257/tools/TaskOutput.txt?surface=compaction - TaskStop: https://changelogs.core-directive.com/prompts/2.1.257/tools/TaskStop.txt?surface=compaction - WebFetch: https://changelogs.core-directive.com/prompts/2.1.257/tools/WebFetch.txt?surface=compaction - WebSearch (changed in this version): https://changelogs.core-directive.com/prompts/2.1.257/tools/WebSearch.txt?surface=compaction - Workflow: https://changelogs.core-directive.com/prompts/2.1.257/tools/Workflow.txt?surface=compaction - Write: https://changelogs.core-directive.com/prompts/2.1.257/tools/Write.txt?surface=compaction ## Full text - system prompt: https://changelogs.core-directive.com/prompts/2.1.257/system.txt?surface=compaction