Prompt capture

v2.1.281 system prompt

CLI The system prompt of v2.1.281, as Claude Code, interactive mode sent it to the model, read out of the request it put on the wire. The text comes first; what changed since the previous capture is further down, kept apart from it.

Released23 Sep 26captured 23 Sep 26

Compared withv2.1.280the previous capture taken the same way

Prompt218 ln27,325 characters

Model strings274 copies of the prompt between them

Tool descriptions27 0 moved this release, 25 with a parameter schema

Captured 6 ways. Each is a separate prompt with its own history, and a change is only ever measured against the previous capture taken the same way, never across these.

Default settings

Claude Code, interactive mode Agent SDK, print mode

a clean sandbox with no stored flags, as a fresh install runs

Seeded with feature flags

Claude Code, interactive mode, seeded with this account's feature flags Claude Code, interactive mode, seeded with anonymous feature flags Agent SDK, print mode, seeded with this account's feature flags Agent SDK, print mode, seeded with anonymous feature flags

the same client started with a stored set of feature flags on, so it can send text a default install does not. What that tells you

Read it The whole system prompt → 218 lines, 27,325 characters, with a reading view and a copy button

As plain textthe same prompt as a .txt, to download or diff
27 tool descriptionsthe text the model is given for each tool
10 appended blocks87,898 more characters the client sends after the system prompt
4 copies by modelthe prompt is not one text; which models get which copy
18 prompts in this releasecompaction, subagents, reminders: each its own request

What changed since the previous capture

0 One line per document that moved, the system prompt and the tool descriptions in the same table.

No change to the system prompt since v2.1.280.

PromptReachMovedThe first line that changed

Nothing in the system prompt or in any of the 27 tool descriptions moved between v2.1.280 and v2.1.281.

The prompt by model

4 The client does not send one system prompt: each model gets its own copy with its name and a few lines worked in. A row is one copy and how many of the 27 model strings get it, most first. Every copy opens with the same line: You are an interactive agent that helps users with software engineering tasks.

#CopyLengthSent toDocuments

1 Haiku, Sonnet and Opus, 17 model strings 218 ln · 27.3k 17 of 27 3 copies

2 Fable and Mythos, 2 model strings 79 ln · 10.2k 2 of 27 2 copies

3 Opus 5 family, 2 model strings 70 ln · 9.3k 2 of 27 1 copy

4 Opus 4.0 to 4.8 family, 6 model strings 56 ln · 5.9k 6 of 27 2 copies

Tool descriptions

27 The text the model is given for each tool, on this arm.

All 27 tool descriptions →

ToolDescriptionCopiesMoved

Agent 1,811 chars 2 ○same

AskUserQuestion 1,786 chars 2 ○same

Bash 1,229 chars 2 ○same

CronCreate 2,924 chars 1 ○same

CronDelete 167 chars 1 ○same

CronList 106 chars 1 ○same

Edit 360 chars 2 ○same

EnterPlanMode 4,011 chars 1 ○same

EnterWorktree 3,220 chars 1 ○same

ExitPlanMode 1,849 chars 1 ○same

ExitWorktree 1,923 chars 1 ○same

ListAgents 777 chars 1 ○same

NotebookEdit 619 chars 1 ○same

Read 790 chars 2 ○same

ReportFindings 574 chars 1 ○same

ScheduleWakeup 3,396 chars 1 ○same

SendMessage 4,259 chars 1 ○same

Skill 1,417 chars 1 ○same

TaskCreate 2,146 chars 1 ○same

TaskGet 732 chars 1 ○same

TaskList 998 chars 1 ○same

TaskStop 378 chars 1 ○same

TaskUpdate 2,243 chars 1 ○same

WebFetch 469 chars 2 ○same

WebSearch 312 chars 2 ○same

Workflow 3,480 chars 1 ○same

Write 240 chars 2 ○same