Free sheets · Model Context Protocol
The worksheets from the free MCP lessons
Each one comes from a lesson you can watch for free: the evidence table, the questions, and the answer key. Read them here or print the PDF. No signup.
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Lesson 1.1 · MCP Production
Your MCP server fails on one replica. Start with the request.
Same MCP tool call, two replicas, two answers. A free sheet for telling what the request carries apart from what one process remembered.
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Lesson 1.2 · MCP Production
One MCP request, field by field.
Every field in one MCP 2026-07-28 request, from the Mcp-Method and Mcp-Name headers to _meta, with what each one proves and what it doesn't.
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Lesson 1.3 · MCP Production
Was it the transport, the protocol or the tool?
A rejected MCP call, sorted from the response alone: HTTP status, JSON-RPC codes like -32020 and -32602, or a tool result with isError set.
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Lesson 2.1 · MCP Production
Your MCP tool timed out. Did the write happen?
A timeout tells you about the wait, not the write. What each observation proves, and why the JSON-RPC id can't stand in for an idempotency key.
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Lesson 3.1 · MCP Production
The tool answered. The approval never came.
The tool answered and nothing happened. Tell input_required from a failure, and check caller, subject, expiry and replay before anything commits.
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Lesson 8.1 · MCP Production
Health check green, MCP tool still failing.
Liveness 200, readiness 200, and the tool call still fails. The incident sheet that separates a delivered tool error from a replica that is down.
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Lesson 9.1 · MCP Production
What MCP 2026-07-28 breaks, and what's only deprecated.
What the stateless MCP 2026-07-28 revision breaks in a 2025-11-25 server, what is only deprecated, and the first thing to inspect for each.