---
type: method
slug: build-custom-gpt-or-skill
title: "Build a custom GPT, Gem or Claude Skill"
category: "AI Setup & Productivity"
subcategory: "AI setup"
level: intermediate
source: https://deepstoryresearch.com/method/build-custom-gpt-or-skill
publisher: Deepstory Research
---

> **How to use this file:** attach it to ChatGPT, Claude, Gemini or Copilot (or paste the prompt section), replace every [PLACEHOLDER] with your details, and add any data or Deepstory evidence files the method needs.

## When to use this method
- A task repeats often enough to deserve its own assistant.

## Prompt

# Build a custom GPT, Gem or Claude Skill
Method by Deepstory Research: deepstoryresearch.com/method/build-custom-gpt-or-skill

You are an AI product builder. Follow the method below step by step. Goal: A custom assistant spec: purpose, instructions, knowledge files, conversation starters and test cases.

## My inputs
- Task the assistant does: [TASK_THE_ASSISTANT_DOES]  (example: turn meeting notes into proposals)
- Users: [USERS]  (example: my sales team)
- Platform: [PLATFORM]  (example: ChatGPT GPT, Gemini Gem, Claude Skill)
- Knowledge files: [KNOWLEDGE_FILES]  (example: templates, pricing)

Before you start: if any input above is still in [BRACKETS] or missing, ask me for it in one short numbered list and wait. Do not guess. If I attached files (data, briefs, Deepstory evidence files), treat them as the primary source.

## Steps to follow
1. Define scope and out-of-scope.
2. Write the instruction set (role, process, output format, rules).
3. List knowledge files and how to use them.
4. Write conversation starters.
5. Write 5 test cases with expected behaviour.
6. Give platform-specific setup steps.

## Deliver the output in this structure
- Scope
- Instructions
- Knowledge plan
- Starters
- Test cases
- Setup steps

## Quality rules
- Instructions must include what to do when inputs are missing.
- Label every number as FACT (with source and date), ESTIMATE (show the calculation) or ASSUMPTION.
- If a Deepstory evidence file is attached, use its figures as the reference values and cite its source references; tag claims that are not from it as [UNVERIFIED].
- End with: the 3 assumptions that matter most, what would change the answer, and the single best next step.

---
Deepstory methods are process guidance for AI tools. Review AI output before relying on it; legal, tax, medical and investment matters need a qualified professional.