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MCP · Building servers and clients

Answer how to actually build an MCP server or client: transports and when to use each, how tools, resources and prompts are declared and called, and the mistakes that make a server work in one client and not another.

576 notes · updated 2026-08-04 · trained 46%

since last sitting: +0 newly passed · −1 lost — this brain is learning

Ask it things like

answers 13/30 on its latest exam
Show me the minimum code to build an MCP server in Python with FastMCP and run it over stdio.Building a server✓
Walk me through the full flow of a client that wires MCP tools into an LLM.Client implementation✓
How do I expose a resource, and how does a client read it?Primitives: resources✓
How should a tool report a failure — throw or return something?Primitives: tools✓
Why does my stdio server break as soon as I add a print/console.log statement?Transports✓
What transports does MCP support, and when should I pick stdio versus Streamable HTTP?Transports✓
How do I declare a prompt and how does a user invoke it?Primitives: prompts✓
What's the difference between a resource and a tool — when should I use each?Primitives: resources✓
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$ claude mcp add --transport http mozg \
https://mozg.sh/mcp --header "Authorization: Bearer …"
> use mozg/mcp-build — …
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What it can answer

30 checks
46%
▲Client implementation3 / 4
▲Transports3 / 5
✓Primitives: resources2 / 2
▲Troubleshooting & ops2 / 5
▲Building a server1 / 4
▲Primitives: prompts1 / 2
▲Primitives: tools1 / 4
✕Cross-client compatibility0 / 4
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Inside

  • Inspector tabs appear based on server capabilities · troubleshooting & ops
  • Inspector Resources tab: templates, MIME types, subscribe · primitives: resources
  • Launch MCP Inspector web client with npx · troubleshooting & ops
  • Inspector --dev flag is web-only · troubleshooting & ops
  • Servers may change registered tools based on advertised extensions · cross-client compatibility
  • Inspector Tools tab renders schema, annotations and results · primitives: tools
  • Inspector host binding defaults and DANGEROUSLY_BIND_ALL_INTERFACES · security
  • Where the Inspector server list comes from per launch flag · troubleshooting & ops
  • Inspector session token guards /api/* routes · troubleshooting & ops
  • Pin or disable the Inspector auth token · troubleshooting & ops
  • Inspector monitoring sidebar (Tasks, Logs, Protocol, Network, Console) · troubleshooting & ops
  • Inspector per-server settings: era, log level, extensions, roots · troubleshooting & ops
  • Pagination of tools/resources/prompts lists · cross-client compatibility
  • Inspector Prompts tab previews generated messages · primitives: prompts

Licence

CC BY-NC-SA 4.0

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