MCP Building Blocks — Tools, Resources & Prompts¶

Every MCP server is built from 3 building blocks. Let's use Cloud Café ☕ to understand each one.

The Cloud Café Kitchen Analogy 🍳¶

Think of your MCP server as the café's kitchen. Every kitchen has three things:

Building Block	In the Kitchen	What It Does
🔧 Tools	The appliances (coffee machine, oven, blender)	Actions — things the AI can do
📦 Resources	The pantry & fridge (ingredients, menus, recipes)	Data — things the AI can read
📝 Prompts	The recipe cards on the wall	Templates — pre-written instructions for common tasks

🔧 Tools — "Do Something for Me"¶

Tools are actions — like pressing a button on a machine. When Copilot needs to do something, it uses a tool.

Cloud Café Examples¶

Tool Name	What It Does	Café Analogy
`list_users`	Show everyone in the system	Check the staff roster
`create_resource_group`	Set up a new storage area	Open a new storage room
`get_service_health`	Check if services are working	Check if equipment is running
`list_licenses`	Show software licences	Check how many loyalty cards are issued

You've Already Used Tools!¶

Every time I reached out to Azure or M365 for you, I was calling a tool:

"List resource groups in my lab" → I called the group_list tool on your Azure MCP server
"How many Copilot licences?" → I called the list_licenses tool on your M365 MCP server
"Show me lab users" → I called the list_users tool

Key Insight

Tools are the most common building block. When people say "MCP server", they usually mean "a collection of tools". Your Azure MCP server has dozens of tools — one for each thing it can do.

📦 Resources — "Let Me Read Something"¶

Resources are data that the AI can look at — like reading a menu or checking the fridge. They're mostly read-only.

Cloud Café Examples¶

Resource	What It Contains	Café Analogy
Today's specials	List of featured items	The specials board
Price list	All items with prices	The menu on the wall
Customer feedback	Reviews and ratings	Comment cards in the box

How Are Resources Different from Tools?¶

	Tools 🔧	Resources 📦
Analogy	Coffee machine (does something)	Menu on the wall (read-only)
Direction	AI asks the server to do something	AI reads data from the server
Example	"Create a new user"	"Show me the user list"
Changes things?	Can change data (create, update, delete)	Usually read-only
Triggered by	The AI decides to use it	The AI requests the data

In Practice

Many MCP servers blur this line — they offer mostly tools and fewer resources. Your Azure MCP server is almost entirely tools. That's completely normal! Resources are more common in MCP servers that serve up documents, files, or reference data.

📝 Prompts — "Here's How to Ask Me Things"¶

Prompts are pre-written templates — like recipe cards pinned above the kitchen counter. They tell the AI how to approach a specific task.

Cloud Café Example¶

Imagine a recipe card pinned in the kitchen that says:

☕ "Daily Café Report" Template:
  1. Check inventory levels
  2. List today's orders
  3. Calculate revenue
  4. Flag items running low
  5. Summarise in a table

Instead of you asking 4 separate questions, you just say:

"Run the daily café report"

...and the MCP server knows the whole recipe!

Real-World Examples¶

Prompt Template	What It Does
`review-pull-request`	Checks code for bugs, security issues, and style — all in one go
`daily-report`	Gathers metrics, summarises health, and flags issues
`onboard-new-user`	Steps through creating account, assigning licences, and notifying the team

Prompts Are a Bonus Feature

Prompts are the least common building block. Many MCP servers don't include any — they just offer tools. Think of prompts as a cookbook that comes with your new oven. Nice to have, but the oven works without it!

How the Three Blocks Work Together¶

Here's what happens when you ask me about your lab:

You: "How many Copilot licences are free in my lab?"

Copilot thinks: I need the M365 MCP server...

  Step 1: Uses a 🔧 TOOL called "list_licenses"
  Step 2: Gets back 📦 RESOURCE data (the licence information)  
  Step 3: Formats the answer for you

Answer: "1 free licence out of 25"

And if a prompt template existed:

You: "Run the licence audit"

Copilot uses the 📝 PROMPT template "licence-audit" which tells it to:
  1. Call 🔧 TOOL "list_licenses" → get licence counts
  2. Call 🔧 TOOL "list_users" → get user list
  3. Compare the two → find who has/hasn't got licences
  4. Format a nice summary with 📦 RESOURCE data

Answer: A complete licence audit report!

Quick Summary¶

Block	One-liner	How Common?	Café Analogy
🔧 Tools	Actions the AI can perform	⭐⭐⭐ Very common	Coffee machine, oven
📦 Resources	Data the AI can read	⭐⭐ Somewhat common	Pantry, fridge, menu
📝 Prompts	Pre-written task templates	⭐ Rare (bonus)	Recipe cards

💡 Remember: You don't need all three! Most MCP servers are just a collection of tools, and that's perfectly fine. It's like a kitchen that has great appliances — you can cook anything, even without recipe cards on the wall.