Custom Instructions for Claude

By default, Claude knows very little about who you are. Every conversation starts from scratch. If you provide some context at the account level, who you are, what you do, and how you prefer to work, every new chat starts much closer to the answer you actually want without requiring you to explain yourself repeatedly.

This is done through Custom Instructions. There are two levels: account-wide preferences that apply to every conversation, and Project Instructions that apply only within a specific Project.

Account-Wide Preferences

Open your profile menu, go to Settings, and find the Personalisation section (sometimes labelled Personal Preferences). Here, you can add information about yourself and how you'd like Claude to respond. For example:

Save your preferences, then start a new chat and ask something generic, such as:

Claude will automatically adapt its response, using British spelling, concise formatting, and minimal fluff. Your preferences are already influencing the output.

Project Instructions Build on Top

Now open the Mitchell Stone Partners Project from Chapter 1 and add Project-specific instructions:

This information becomes part of the Project's context. If you start a new chat inside that Project and ask:

Claude combines both layers of instructions. It uses your preferred style (concise, bullet-based, British English) while also adapting to Chris's preferences (conversational, data-focused) and highlighting billing implications where relevant. The two layers work together:

• Account-wide preferences shape every conversation;
• Project Instructions shape conversations within a specific Project.

Both can be updated at any time. There is no need to create the perfect setup immediately. Start with a few useful details, then refine your instructions as you notice patterns in the information you repeatedly provide to Claude.