0x10Lesson 2 of 16

Compare tools, resources, and prompts

Learn the three server primitives and who decides when each one is used.

16 min 7-question quiz 1 code exercise

By the end of this lesson you can

Choose whether a capability fits a tool, resource or prompt
Explain who controls each primitive
Name the requests a client uses for each

Servers offer three kinds of capability, and the key difference is who decides when to use them:

Primitive	What it is	Controlled by	List / use
Tool	An action: search, create, send	The model decides to call it	`tools/list`, `tools/call`
Resource	Data to read, named by a URI: a file, a schema	The application decides what context to include	`resources/list`, `resources/read`
Prompt	A reusable template, often shown as a slash command	The user picks it	`prompts/list`, `prompts/get`

The same underlying data can be offered more than one way: a database could expose a run_query tool and a schema://tables resource.

Try it

Up to 15 XP

Tool, resource or prompt?

For each capability, choose the primitive that fits best. Ask: is it an action, a piece of context, or a template the user picks?

0 of 6 sortedScore 0/0

“Create a calendar event”
“The contents of README.md”
““/review-pr” - a template asking for a thorough code review”
“Search the web for a phrase”
“A database’s table definitions”
““/summarize-meeting” with a transcript argument”

route.py

methods = {"tool": "tools/call", "resource": "resources/read", "prompt": "prompts/get"}
for kind, name in [("tool", "get_weather"), ("resource", "file:///notes.md"), ("prompt", "code_review")]:
    print(methods[kind], name)

Output

tools/call get_weather
resources/read file:///notes.md
prompts/get code_review

Key takeaways

Tools are actions (model-controlled), resources are readable context (application-driven), prompts are templates (user-controlled).
Each has a …/list request for discovery and its own request for use.
A prompt or resource is not an access-control mechanism - authorization is separate.

Lesson quiz

7 questions · pass with 5 correct · up to 50 XP

Passing this quiz completes the lesson and keeps your streak going. Questions you miss come back in review sessions later.

Practice: build an MCP server

Write Python in the editor and run it against sample inputs. Python runs locally in your browser using a WebAssembly runtime.

Exercise 1

Route capability requests

+25 XP

Each input line is a capability kind (tool, resource or prompt) and its name or URI. Print the request method a client uses to invoke it, followed by the name: tools/call NAME, resources/read URI or prompts/get NAME. Read lines until the input ends.

One of each
Two tools

main.py

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