#### System prompt flags in resumed conversations
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124124| `--strict-mcp-config` | Only use MCP servers from `--mcp-config`, ignoring all other MCP configurations. See [Exclusive control with managed-mcp.json](/docs/en/managed-mcp#exclusive-control-with-managed-mcp-json) for what the flag does under a managed MCP file | `claude --strict-mcp-config --mcp-config ./mcp.json` |
125125| `--system-prompt` | Replace the entire system prompt with custom text | `claude --system-prompt "You are a Python expert"` |
126126| `--system-prompt-file` | Load system prompt from a file, replacing the default prompt | `claude --system-prompt-file ./custom-prompt.txt` |
127| `--system-prompt-snapshot` | Pass `off` to rebuild the system prompt on every request instead of reusing the prompt [recorded on the conversation's first request](#system-prompt-flags-in-resumed-conversations), for example while you iterate on `--append-system-prompt` text across `--continue` runs. Requires Claude Code v2.1.257 or later | `claude --system-prompt-snapshot off` |
127128| `--teleport` | Resume a [web session](/docs/en/claude-code-on-the-web) in your local terminal | `claude --teleport` |
128129| `--teammate-mode` | Set how [agent team](/docs/en/agent-teams) teammates display: `in-process` (default), `auto`, `tmux`, or `iterm2` (added in v2.1.186). Overrides the [`teammateMode`](/docs/en/settings-reference#teammatemode) setting for this session. See [Choose a display mode](/docs/en/agent-teams#choose-a-display-mode) | `claude --teammate-mode auto` |
129130| `--tmux` | Create a tmux session for the worktree. Requires `--worktree`. Uses iTerm2 native panes when available; pass `--tmux=classic` for traditional tmux | `claude -w feature-auth --tmux` |
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134135
135136### System prompt flags
136137
137Claude Code provides four flags for customizing the system prompt. All four work in both interactive and non-interactive modes.
138Claude Code provides five flags for customizing the system prompt. Four set its text, and with `--system-prompt-snapshot` you control whether a conversation keeps the text it started with. All five work in both interactive and non-interactive modes.
138139
139| Flag | Behavior | Example |
140| :---------------------------- | :------------------------------------------ | :------------------------------------------------------ |
141| `--system-prompt` | Replaces the entire default prompt | `claude --system-prompt "You are a Python expert"` |
142| `--system-prompt-file` | Replaces with file contents | `claude --system-prompt-file ./prompts/review.txt` |
143| `--append-system-prompt` | Appends to the default prompt | `claude --append-system-prompt "Always use TypeScript"` |
144| `--append-system-prompt-file` | Appends file contents to the default prompt | `claude --append-system-prompt-file ./style-rules.txt` |
140| Flag | Behavior | Example |
141| :---------------------------- | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :------------------------------------------------------------------------- |
142| `--system-prompt` | Replaces the entire default prompt | `claude --system-prompt "You are a Python expert"` |
143| `--system-prompt-file` | Replaces with file contents | `claude --system-prompt-file ./prompts/review.txt` |
144| `--append-system-prompt` | Appends to the default prompt | `claude --append-system-prompt "Always use TypeScript"` |
145| `--append-system-prompt-file` | Appends file contents to the default prompt | `claude --append-system-prompt-file ./style-rules.txt` |
146| `--system-prompt-snapshot` | With `off`, rebuilds the prompt on every request. With `on`, the default, reuses a recorded prompt where [recording applies](#system-prompt-flags-in-resumed-conversations) | `claude --append-system-prompt "Draft rules" --system-prompt-snapshot off` |
145147
146148`--system-prompt` and `--system-prompt-file` are mutually exclusive. The append flags can be combined with either replacement flag.
147149
148150Choose based on whether Claude Code's default identity still fits your task. Use an append flag when Claude should remain a coding assistant that also follows your extra rules: per-invocation instructions, output formatting, or domain context for a `-p` script. Appending preserves the default tool guidance, safety instructions, and coding conventions, so you only supply what differs. Use a replacement flag when the surface, identity, or permission model differs from Claude Code's, like a non-coding agent in a pipeline that no human watches. Replacing drops all of the default prompt, including tool guidance and safety instructions, so you take responsibility for whatever your task still needs.
149151
150These flags apply only to the current invocation. For persistent personas you can switch between and share across a project, use [output styles](/docs/en/output-styles). For project conventions Claude should always follow, use [CLAUDE.md](/docs/en/memory). The [Agent SDK guide on system prompts](/docs/en/agent-sdk/modifying-system-prompts#decide-on-a-starting-point) covers the same decision in more depth.
152For persistent personas you can switch between and share across a project, use [output styles](/docs/en/output-styles). For project conventions Claude should always follow, use [CLAUDE.md](/docs/en/memory). The [Agent SDK guide on system prompts](/docs/en/agent-sdk/modifying-system-prompts#decide-on-a-starting-point) covers the same decision in more depth.
153
154#### System prompt flags in resumed conversations
155
156By default, Claude Code builds the system prompt once, on a conversation's first request, with the text from any system prompt flags applied, and records it in the session. Until the conversation is compacted, every later request uses that recorded prompt, including after you return to the conversation with `--resume` or `--continue`. If you pass different system prompt flag text, or none, on that later launch, it takes effect once the conversation is compacted or when you start a new conversation.
157
158Recording applies in sessions that [fetch feature flags](/docs/en/env-vars#features-that-need-feature-flag-fetching), as sessions signed in with a claude.ai or Console account do by default. On Amazon Bedrock, Google Cloud's Agent Platform, Microsoft Foundry, and in other sessions that don't fetch them, Claude Code rebuilds the prompt on every request and `--system-prompt-snapshot` has no effect. If you start Claude Code in [bare mode](/docs/en/headless#start-faster-with-bare-mode), by passing `--bare` or setting `CLAUDE_CODE_SIMPLE=1`, recording stays off unless you pass `--system-prompt-snapshot on`.
159
160To rebuild the prompt on every request instead, for example while you iterate on its wording across `--continue` runs, pass `--system-prompt-snapshot off`. Before v2.1.265, passing any of the system prompt flags also turned recording off unless you passed `--system-prompt-snapshot on`.
151161
152162## See also
153163