The concept
All four use AI, but they do different jobs:
- Microsoft Copilot Studio: low-code agents for people who work in Microsoft 365 and Teams (Days 77–84).
- Claude (API, Agent SDK, Claude Code): build your own agent into your own app or workflow, in code (Days 66–75).
- OpenAI Codex: a coding agent that writes, tests and reviews code, in a terminal, IDE or cloud (Days 61–65).
- GitHub Copilot: AI in your editor and on GitHub, from completions to issue-to-pull-request (Days 55–60).
The first two build agents for other people. The last two (plus Claude Code) help you write the code.
The 4 questions
1. Who builds it: makers with no code, or developers?
2. Where do users work: Teams and Microsoft 365, or your own app?
3. What's the output: an agent for end users, or code for your repo?
4. What must it connect to, under whose rules?
Walkthrough: 4 requests, 4 answers
- Insurance underwriters want a Teams assistant answering from guidelines in SharePoint. No developers. → Copilot Studio.
- A bank's payments team wants an agent in its own case system, calling internal APIs. → Claude API or Agent SDK, built by developers.
- A retail analytics team must upgrade 40 old report scripts, tests passing. → a coding agent: Codex, Claude Code or the Copilot coding agent. Use the one your team already has.
- A health-tech developer wants help while typing in VS Code, every day. → GitHub Copilot.
These overlap. Tie-breakers: where users already work, what your company licenses and approves, and who maintains it.
Where you see it at work
- Product management: tool choice is a scope decision; put it in the brief.
- Business analysis: question 4 is your integration and security requirements.
- Banking, insurance, healthcare: compliance often answers question 4 for you. Ask early.
Try it today (10–15 min)
1. Write one agent idea from your job in one sentence.
2. Answer the 4 questions for it.
3. Map it to a tool, open its docs and confirm one feature you need:
https://learn.microsoft.com/en-us/microsoft-copilot-studio/fundamentals-what-is-copilot-studio
https://platform.claude.com/docs/en/agents-and-tools/tool-use/overview
https://developers.openai.com/codex
https://docs.github.com/en/copilot
In one sentence
Pick the tool by who builds it, where users work, what it produces and what it must connect to, not by which demo looked best.
Which of the 4 requests looks most like yours? 👇