Series overview
1 July 2026 6 min read 34 min full series Series The tool choice should follow the shape of the work.

Part 1: Decide What to Build

How to decide whether the work belongs in a prompt, skill, agent, workflow builder or custom app.

Sources are listed at the end; recommendations are decision guidance, not legal, security or procurement advice.

01

The Sharing Question Is the Real Test

"Can I share it?" sounds simple.

It is not. There are at least five different things people mean when they ask that question.

Layer 1Prompt
What you share

Instructions someone can copy.

Where it breaks

Inconsistent, hard to govern and easy to drift.

Layer 2Skill
What you share

A repeatable method with instructions, files, scripts or resources.

Where it breaks

Still needs a user surface, lifecycle owner and quality control.

Layer 3Agent
What you share

A bot colleagues can use in Teams, Slack, ChatGPT or a similar surface.

Where it breaks

The user experience and workflow are constrained by the host platform.

Layer 4Workflow
What you share

A structured process in Retool, Power Apps, AppSheet or another builder.

Where it breaks

Fragile click-ops if nobody owns versions, permissions and testing.

Layer 5App
What you share

An owned interface, data model, auth layer, logging and release process.

Where it breaks

Higher ownership burden, support model and engineering responsibility.

This is the real difference between productivity tooling and internal product building.

A prompt helps a person repeat a thought process. A skill helps a team reuse a method. An agent helps colleagues invoke a capability. An app helps an organisation run a process.

Those are different jobs.


02

Where Microsoft Copilot Fits

Microsoft's advantage is distribution.

If your company already lives in Teams, Outlook, SharePoint, Word, Excel and PowerPoint, Microsoft is not just selling an AI model. It is selling an AI layer over the existing work graph.

That matters. With Copilot Studio, agents can be published to channels such as Teams, Microsoft 365 Copilot, SharePoint, websites, mobile apps and Azure Bot Service channels. Microsoft's publishing lifecycle also makes the enterprise route explicit: test the agent, publish it, configure channels, make it available in Teams or Microsoft 365 Copilot, then roll out more broadly after testing.1

For internal use, authentication is the important bit. Microsoft describes no authentication, Microsoft authentication and manual authentication options for Copilot Studio. It also warns that no authentication means anyone with the link can chat with the agent, while Microsoft authentication uses Entra ID and unlocks Teams and Microsoft 365 channels.2 The practical takeaway is straightforward: anonymous access is for public-style scenarios; internal and user-specific agents need identity and permissions aligned to the organisation.

Copilot is strongest when

The answer should live where people already work: a policy assistant in Teams, a proposal helper in Microsoft 365, a departmental workflow in familiar Microsoft surfaces, or a lightweight agent that can be mentioned in a team channel.

It also creates the first big trade-off.

A Teams bot is not a case-management system. A Copilot response is not a review queue. A chat transcript is not a proper audit trail. A published agent is not automatically a product.

That does not make Copilot Studio weak. It means it has a centre of gravity. Its centre of gravity is governed productivity inside the Microsoft estate.


03

Where Claude Fits

Claude feels different.

Microsoft is strongest when the work graph is the product. Claude is more interesting when the work tips into craft: reasoning, writing, analysis, coding, reusable expertise and agentic work that still sits close to files and code.

The important piece here is Claude Skills. A Skill is a reusable capability package built around a SKILL.md file. It can include instructions, supporting files, scripts and resources, and Claude loads it when relevant instead of forcing you to paste the same procedure into chat every time.3

The sharing model is also more developer-friendly than many productivity tools. Claude Code skills can live at enterprise, personal, project or plugin scope. Project skills can sit in the repo. Plugin skills can be namespaced and distributed through plugin structures. Claude Code settings also have user, project, local and managed scopes, which matters when a team wants repeatable behaviour without giving up organisational control.34

That is less like "publish a bot to the company app store" and more like "package this expertise so it can be reused across projects, teams and codebases".

For AI solutions engineers, that matters. A consultancy method can become a Skill. A delivery checklist can become a reusable instruction pack. A document transformation workflow can become a versioned capability. A coding standard can become part of the project context.

You can use Claude for thinking.

You can use Skills for repeatability.

You can use Claude Code for implementation.

But once you build a serious custom agent, you are back in software-engineering land: persistence, scaling, observability, authentication, secrets, concurrency, cost and multi-tenant isolation. Claude can help you build the thing. It does not remove the need to own the thing.


04

OpenAI, Gemini, Retool and Streamlit Sit in the Middle

The market is not just Copilot versus Claude.

OpenAI has moved further into programmable agent workflows, with documentation that treats agents as applications with orchestration, tools, state, guardrails, human review, observability and evaluation loops.5 Gemini belongs in the broader comparison when the organisation is Google-heavy. Then there is the practical middle layer: tools like Retool and Streamlit.

Retool is useful when the thing should feel like an internal app quickly. It has real concepts for apps, resources, workflows, agents, RBAC and permission groups that control access to objects across the organisation.6 That makes it sensible when chat is too loose but a fully bespoke React app is too much.

Streamlit is useful when the fastest route to value is a Python-first app: analyst workbenches, evaluation dashboards, RAG prototypes, model comparison tools and internal demos that need to become usable quickly. Streamlit supports user authentication with OpenID Connect providers such as Google, Microsoft Entra ID, Okta and Auth0, but its documentation is clear that OIDC provides authentication, not authorisation.7

That last point is the giveaway. The moment you say "authorisation is something we need to design", you are no longer just playing with a productivity tool. You are building a product boundary.


05

When the Agent Should Become an App

Here is the practical test I would use.

Keep it as a productivity tool or shared agent when

  • The work is mostly drafting, summarising, researching or analysing.
  • The workflow already happens in Teams, Outlook, Slack or Docs.
  • The user can judge the output before it matters.
  • The process is still changing every week.
  • There is no durable state beyond the conversation.

Build an app when

  • There are distinct user roles, permissions or client boundaries.
  • The workflow has stages, queues, assignments or reviews.
  • Outputs require approval, traceability or audit history.
  • The same process is repeated across teams or clients.
  • People keep asking where the latest version lives.

The clearest warning sign is when people start building process around the agent: a spreadsheet to track requests, a Teams channel to chase approvals, a manual checklist to validate outputs, a folder full of prompt versions, or one person who knows how it all works only because they built it.

That is usually the moment to ask whether the agent has become the wrong container for the work.