Claude personalizes its replies through three layered features: Instructions for Claude (an account-wide system prompt set in Settings), Styles (per-chat tone, voice, vocabulary, and detail-level presets), and Project instructions (per-workspace inside Claude Projects). Set Instructions for Claude under Settings > General > Profile so they apply to every new chat. Open the plus menu in any chat and hover Use style to pick a built-in preset (Normal, Learning, Concise, Explanatory, Formal) or click Create & edit styles to build a custom Style from a writing example or a prompt. Styles apply per chat from a feather chip in the compose toolbar; Instructions for Claude apply everywhere. Per the official Anthropic docs, Styles are moving to Skills as part of a broader personalization rollout, but both UI surfaces work in 2026. Free on every Claude plan. Verified June 2026.

How to Set Up Claude Custom Instructions and Styles (2026)

Claude's personalization stack is the most flexible of the three big assistants in 2026: not one global system prompt, but three layered features that stack together. Instructions for Claude (what Anthropic's docs still describe as "custom instructions") set an account-wide rulebook in Settings. Styles let you swap tone and voice presets per chat from the Use style menu. Project instructions (covered in our Claude Projects guide) scope behavior to a single workspace. All three stack on every reply. This guide walks the full personalization flow with screenshots from June 2026: setting Instructions for Claude, picking a built-in Style, creating a custom Style called Brand Voice, applying it from the chat compose toolbar, and editing it later. It also shows where the Claude module of AI Toolbox (formerly Claude Toolbox) picks up afterward: full-text search across every Claude message (so you can find the chat where you first dialed your Style in), message-level bookmarks, and per-conversation TXT or JSON export. AI Toolbox is part of the same unified Chrome install that powers our ChatGPT and Gemini modules.

What Are Claude Custom Instructions?

Custom instructions in Claude are now called Instructions for Claude. They are an account-wide system prompt you set once in Settings that Claude keeps in mind across every chat. Anthropic's official documentation places them at Settings > General > Profile and describes the scope directly: "Claude will keep these in mind across chats and Cowork within Anthropic's guidelines." Use them to record your preferred approaches and methods, common terms or concepts you use, typical scenarios you encounter, and general communication preferences. They are not a replacement for prompting; they are the standing rules every prompt runs against.

What goes in Instructions for Claude in practice: your role and what you build, format preferences (answer-first, plain numbers over vague qualifiers), what to avoid (em dashes as punctuation, emojis), language conventions (British spelling for international audiences), and any standing assumption-checking rules (always confirm assumptions before writing long replies). Keep them prescriptive and concrete. "Be helpful" is a non-instruction; "always confirm assumptions before writing long replies" is one Claude can check on every reply.

Step 1: Pick a Built-in Style From the Plus Menu

In any Claude chat, click the plus icon next to the prompt input and hover Use style at the bottom of the menu. The fly-out lists five built-in Styles with a feather icon next to each: Normal (default, currently selected on a fresh account), Learning, Concise, Explanatory, and Formal. Below the presets, a + Create & edit styles entry opens the full Style editor. Click any preset to apply it to the current chat. The plus menu also shows a separate Skills entry above Use style, which is where Anthropic's "Styles are moving to skills" migration is landing in 2026; for now both surfaces exist side by side.

Pick built-in Styles for one-off tone changes: Concise when you need a short answer fast, Learning when you want Claude to teach step by step, Formal when the reply is going into a customer-facing document. For your own brand voice, jump to Step 2 and build a custom Style instead.

Step 2: Open Customize Your Styles and Create a Custom Style

Click + Create & edit styles in the Use style fly-out to open the Customize your styles modal. The modal lists the four editable presets (Learning, Concise, Explanatory, Formal) each marked with a Preset tag, a Tip explaining what Styles do ("Choose from preset styles or create your own custom style to tailor elements of Claude's written responses such as tone, voice, vocabulary, detail level, and more."), and a dark Create custom style button in the bottom-left with a feather icon. Click Create custom style to start the new-Style flow. Note that Normal does not appear in the Customize list because it is the no-Style baseline, not an editable preset.

Use custom Styles for any tone you re-use often: a brand voice, a customer-support voice, a research-summary voice, a code-review voice. Once saved, the Style sits in the Use style menu alongside the presets and can be toggled on or off per chat without re-explaining your preferences each time.

Step 3: Describe Your Style (Define Style Objective)

In the Create a style flow, click Describe style instead under the Add writing example button, then pick a starting point from the left rail and describe your style in the textarea on the right. Claude offers five starting points: Define style objective (the default, blue-highlighted; "Describe the main purpose and goal of this writing style, whether to teach, analyze, persuade, inspire, etc."), Tailor to an audience, Use specific voice & tone, Describe generally, and Use custom instructions (advanced). For our Brand Voice we typed: "Match a productivity-blog tone: friendly but professional, plain numbers, no marketing fluff, no em dashes, no emojis. Open every reply with the direct answer in one sentence before any context." Click Generate style to save with Define style objective, or switch to Use custom instructions (advanced) and click Create style for verbatim wording.

Define style objective is the right starting point for almost every brand-voice case: it generates a polished Style summary from your description and turns into a Style summary like "Deliver direct, friendly guidance with professional clarity and no unnecessary embellishment". If you want to control every word of the Style instructions, use Use custom instructions (advanced) and skip the generation step.

Step 4: See Your Custom Style Saved in Customize Your Styles

After clicking Generate style or Create style, the new Style joins the list in the Customize your styles modal alongside the built-in presets. In our screenshot, Brand Voice appears at the bottom of the list under Learning, Concise, Explanatory, and Formal. Built-in presets keep their Preset tag; the custom Brand Voice row has no tag, which is how Claude distinguishes user-created Styles from built-in ones. Drag the grid handle on the left of any row to reorder Styles in the Use style menu, or hover a row to reveal an edit icon for changing the Style later.

Custom Styles are unlimited in 2026 on every plan; the practical limit is your own ability to remember which Style is which. Three to five custom Styles covering distinct contexts (brand voice, customer support, technical writing, research summaries) is usually enough.

Step 5: Apply the Style to a Chat From the Compose Toolbar

Back in any chat, open the plus menu, hover Use style, and click your custom Style name. A feather icon chip appears next to the plus button in the compose toolbar, with the Style name shown on hover. In our screenshot, the Brand Voice chip is active (purple-highlighted feather icon plus an X to remove it) and the tooltip reads "Brand Voice". The chip stays for the duration of this chat. Click the X to remove the Style and revert to Normal for the current chat. Switching Styles mid-chat is fine; the new Style applies from the next message onward. Styles are per-chat, not per-account, so the next new chat starts back on Normal unless you switch again from the menu.

One practical habit: pair your custom Style with Instructions for Claude. Use Instructions for Claude for things that should hold across every chat (assumption-checking, no em dashes, your role and product context), and use Styles for tone presets you swap in and out (brand voice for marketing chats, formal for legal drafts, learning for tutoring).

Search every Claude chat by what you said inside it. Claude's native search finds conversations by title. On paid plans (Pro, Max, Team, Enterprise), Claude also offers conversational RAG search via natural-language queries, scoped per-project. AI Toolbox (formerly Claude Toolbox) adds full-text search across all message content with an Exact match toggle, plus message-level bookmarks with scroll-to and highlight, and per-conversation TXT or JSON export. Free plan: 5 search results per query, 2 bookmark conversations. Premium: unlimited at $9.99 per month or $99 lifetime. Working across ChatGPT, Gemini, and Claude? All Access Lifetime ($149) covers all three modules and saves $148 versus three single-platform Lifetimes ($99 x 3 = $297). See the Claude module →

Step 6: Edit a Style Later (Edit With Claude or Manually)

Open Customize your styles, click the pencil icon next to your custom Style, and Claude shows two editing modes side by side: Edit with Claude (natural-language tweaks) on the left, and Edit style instructions manually (verbatim editing) on the right. Edit with Claude is the fast iteration loop: the panel shows your current Style summary at top ("Deliver direct, friendly guidance with professional clarity and no unnecessary embellishment") and offers two example tweaks as clickable chips, A bit more direct and Much less friendly, plus an "Ask Claude to edit the style..." input where you can type any change in plain English. Edit style instructions manually shows the full prose Style instructions in a large textarea so you can revise them word by word. Both modes save with the same Save changes button in the top-right; Cancel discards.

Use Edit with Claude when you want to nudge the tone (less formal, more concrete, less repetitive). Use Edit style instructions manually when you need a precise wording change (swap "British spelling" for "American spelling", or add a specific rule you missed at creation). Built-in preset Styles (Normal, Learning, Concise, Explanatory, Formal) cannot be edited; if you want a tweaked preset, duplicate it into a custom Style first.

Are Styles Becoming Skills in Claude?

Yes. Anthropic's official documentation states verbatim that "Styles are moving to skills" as part of a broader personalization rollout in 2026. Skills extend the same idea (saved, repeatable Claude behaviors) but add the ability to apply specialized expertise or define behaviors that go beyond writing style alone. The migration is in progress: Claude's plus menu in June 2026 still shows both Skills and Use style as separate items, and Customize your styles is still the canonical Style editor. Anthropic's note on the rollout: "If you previously used a default style or created custom styles, see styles are moving to skills." When the migration completes, your existing custom Styles should be available through the Skills surface without re-creation.

Practical implication for new posts and content workflows: the writing you do today inside custom Styles will carry forward. The UI labels will change (Customize your styles becomes a Skills surface) but the personalization layer underneath is the same. If you are picking which feature to invest in now, custom Styles are the safe choice; they have a documented migration path to Skills.

How Claude Personalization Compares to ChatGPT and Gemini

Claude is the only one of the three big assistants with a per-chat tone preset system (Styles) on top of an account-wide custom instructions system. ChatGPT has custom instructions and a Personality picker (Default, Cynic, Robot, Listener, Nerd) but no per-chat custom-tone presets; tone changes are baked into Personality choice or per-prompt instructions. Gemini has Personal Intelligence (a small set of stable preferences carried across chats) but no Styles equivalent; per-chat tone changes are per-prompt instructions only.

Frequently Asked Questions

What are Claude custom instructions?

Custom instructions in Claude are now called Instructions for Claude. They are an account-wide system prompt you set once in Settings that Claude keeps in mind across every chat. Use them to record preferred approaches, common terminology you use, typical scenarios, and general communication preferences. They work alongside Project instructions (per workspace) and Styles (per chat) without overriding either.

Where do I set Instructions for Claude?

Click your initials in the lower-left of Claude, select Settings, then under General you will see Profile with an Instructions for Claude textarea. Paste your style guide, preferred terminology, and any standing rules, then they apply to every new chat automatically. The subtitle confirms the scope: Claude will keep these in mind across chats and Cowork within Anthropic's guidelines.

What is a Claude Style?

A Claude Style is a saved tone, voice, vocabulary, and detail-level preset you can apply per chat from the plus menu. Claude ships five built-in Styles (Normal, Learning, Concise, Explanatory, Formal) and lets you create your own. Custom Styles can be generated from a writing example, a starting-point objective (Define style objective, Tailor to an audience, Use specific voice and tone, Describe generally), or fully manual custom instructions.

How do I create a custom Style in Claude?

Open the plus menu in any chat, hover Use style, click Create & edit styles, then click Create custom style in the Customize your styles modal. Either paste a writing example or click Describe style instead, then describe your style or paste exact custom instructions and click Generate style or Create style. The new Style joins the built-in presets in the Use style menu and the Customize your styles list.

How do I apply a Style to a Claude chat?

Open the plus menu next to the prompt input, hover Use style, and click any preset or custom Style name. A feather icon chip appears next to the plus button in the compose toolbar with a tooltip showing the Style name. Click the X on the chip to remove the Style for the current chat. Styles apply per chat, not account-wide; the next new chat starts back on Normal unless you switch again.

Can I edit a Claude Style after I save it?

Yes. Open the Customize your styles list, click the pencil icon next to your custom Style, and either Edit with Claude (describe the change in natural language like A bit more direct or Much less friendly) or Edit style instructions manually (paste exact custom instructions text). Click Save changes when done. Built-in preset Styles (Normal, Learning, Concise, Explanatory, Formal) cannot be edited.

Are Styles becoming Skills in Claude?

Yes, Anthropic's documentation states that Styles are moving to Skills, a broader feature that customizes how Claude communicates, applies specialized expertise, or defines repeatable behaviors. The migration is in progress: the plus menu currently shows both Skills and Use style as separate items in 2026. Existing custom Styles will be available through the Skills surface after the migration; functionality stays the same.

What is the difference between Instructions for Claude, Project instructions, and Styles?

Instructions for Claude apply account-wide to every chat (set once in Settings). Project instructions apply only inside a specific Claude Project (set per Project). Styles apply per chat from the Use style menu and tune tone, voice, vocabulary, and detail level. All three stack together: the Project's instructions plus the account's Instructions for Claude plus the chosen Style run together on every reply.

Pair Claude Personalization With AI Toolbox

Claude's Instructions for Claude, Styles, and Project instructions solve the "how should Claude write" problem. AI Toolbox (formerly Claude Toolbox) solves the "where did we discuss that" problem: full-text search across every Claude message (something Claude does not offer natively on any plan), message-level bookmarks with scroll-to and highlight (2 conversations free, up to 1,000 bookmarks on Premium), per-conversation TXT or JSON export, and a multi-language UI (10 locales with RTL). Free plan: 5 results per query, 2 bookmark conversations. Premium: unlimited at $9.99 per month or $99 lifetime. Cross-platform users can grab All Access Lifetime ($149), which covers the ChatGPT, Gemini, and Claude modules in one purchase and saves $148 versus three single-platform Lifetimes ($99 x 3 = $297). Add it from the Chrome Web Store; works on every Chromium browser (Chrome, Edge, Brave, Opera, Arc), not Firefox or Safari.

Conclusion

Claude's personalization stack is the most flexible of the three big assistants in 2026: Instructions for Claude as the account-wide rulebook, Project instructions for per-workspace scoping, Styles for per-chat tone presets. Six clicks gets you from a blank account to a fully-personalized Claude: paste rules into Settings, open the plus menu, hover Use style, pick a preset or build a custom Brand Voice, apply with one click, edit later with Edit with Claude or manual instructions. When the chats stack up, pair Claude with the Claude module of AI Toolbox so you can search and export every conversation your personalized Claude has ever produced.

Last updated: June 1, 2026