AI Chatbots are widely adopted tools available on platforms ranging from small smartphones to high-performance workstations. Despite being general-purpose, large language models can be customized for specific applications. Gemini Gems come into play here. This guide details how to set up a custom Gemini chatbot and outlines the best practices for instructing it.
Step-by-step guide to building a custom Gemini chatbot
You can create custom Gemini Gems using the Gemini web app, but you’ll need to upgrade your personal Google Accounts to Gemini Advanced. Contact your Google Workspace administrator to set up Gemini Advanced for work or school accounts. When you have access, follow this framework to build a Gemini gem:
- Open gemini.google.com.
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Click Gem manager in the lower-left corner.
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Select New Gem.
- Name your Gem and write clear, structured instructions for it to follow.
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Enter a prompt on the right side to preview how Gem responds.
- Click Save and finalize your Gem.
How to write clear and structured instructions for Gemini Gems
Well-structured Gemini Gem instructions customize responses to your preferences. Define the persona, task, context, and format to generate relevant outputs. The following breakdown details each component and its effective use.
Choosing the right persona and tone for your Gemini Gem
Persona defines Gemini’s response style. Specify whether it acts as a professional expert, friendly assistant, or creative writer. This choice sets the tone: formal, conversational, technical, or entertaining. For example, instruct Gemini to explain complex topics as a mentor or offer engaging explanations as a blogger.
Setting up clear objectives for your Gemini chatbot
Outline your objective to guide Gemini’s response. Specify whether you need a summarization, rewrite, analysis, step-by-step guidance, or creative content generation.
Adding relevant context to improve Gemini’s accuracy
Provide context so Gemini understands your request. Include background details such as audience type, industry specifics, technical constraints, or style guides.
Format Gemini’s responses for better readability
Define the format to structure responses as expected. To improve readability, specify bullet points, numbered lists, tables, short paragraphs, or word limits.

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How to improve Gemini’s responses with document uploads
Upload files to give Gemini Gem access to documents and refine its responses. When uploaded, Gemini can summarize reports, PDFs, and research papers; analyze spreadsheets and tabular data; extract details from legal documents, contracts, or technical papers; and generate content based on provided guidelines.
You can upload up to 10 files at a time, each up to 100 MB, or a code folder with up to 1,000 files totaling 100 MB. Ensure files are in a compatible format before uploading.
Plain text files |
.txt |
Code files |
.c, .cpp, .py, .java, .php, .sql, .html |
Document files |
.doc, .docx, .pdf, .rtf, .dot, .dotx, .hwp, .hwpx |
Google Docs & Sheets |
Documents and spreadsheets in Google Drive |
Tabular data files |
.csv, .tsv |
Spreadsheet files |
.xls, .xlsx |
Follow these steps to add files from your device or Google Drive.
- Click Upload files in the Gemini interface.
- Select up to 10 files from your local storage.
- Confirm the upload.
To add files from Google Drive:
- Click Drive in the Gemini interface.
- Turn on Gemini Apps Activity for integration.
- Select and confirm the document.
If Google Workspace is not connected, activate it when prompted for file access.
How Gemini can improve your chatbot instructions
If you need to improve Gem instructions, use Gemini. When creating a new Gem or duplicating an existing one, click the magic wand icon at the bottom of the text box to rewrite and expand your instructions. According to Deven Tokuno, the product lead for Gemini Gems:
Not only does it craft comprehensive instructions, but it also helps them learn how to write like a prompt engineer, showcasing what good instructions look like. It’s a great way to get inspiration — and if you don’t like it, you can undo it or edit it.
For example, if the draft instruction is “Help me write a blog post,” the magic wand can turn it into the following:
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Purpose and goals:
- Create engaging, well-structured blog posts on diverse topics.
- Guide users through brainstorming, drafting, and editing.
- Provide suggestions to improve style and structure.
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Initial inquiry:
- Greet the user and express readiness to help.
- Ask for the blog post topic.
- Offer topic suggestions if the user is uncertain.
- Inquire about the target audience and purpose (for example, inform, entertain, persuade).
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Brainstorming and outlining:
- Assist with idea generation and outline development.
- Recommend relevant subtopics, supporting points, or anecdotes.
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Drafting and editing:
- Help draft the initial blog post.
- Provide tips on grammar, style, and sentence structure.
- Identify and correct errors or inconsistencies.
- Prompt revisions until the final product is complete.
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Overall tone:
- Maintain a supportive tone.
- Offer constructive feedback to improve writing skills.

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Modifying existing Gemini Gems to meet your needs
If you’re new to the platform, begin with pre-made Gemini Gems instead of creating one from scratch. If a pre-made Gem nearly meets your needs but requires adjustments, copy it and customize the instructions. Explore pre-built Gemini Gems designed for everyday tasks, such as Brainstormer, Career Guide, Coding Partner, Learning Coach, and Writing Editor. Access these Gems in Gemini’s left panel under Gems or in the Gem manager.
Experiment and refine your Gemini Gems over time
Your Gemini Gems can be refined over time. Update them based on your experience. Experiment with different instructions and provide feedback to improve performance. This iterative approach reveals new features you had no idea were possible.