---
title: "MCP Articles | Len P. van der Hof"
description: How a Model Context Protocol connection is authenticated, and why a valid connection is not permission to call each tool.
image: "https://lenvanderhof.com/photos/len-portrait-1.jpg"
---

Tag

# MCP

How a Model Context Protocol connection is authenticated, and why a valid connection is not permission to call each tool.

AI Systems

## [A successful tool call is not a verified claim: where MCP assurance stops](https://lenvanderhof.com/en/blog/a-tool-call-is-not-a-verified-claim/)

The fetch can succeed while the memo gets the meaning wrong. Check which document arrived, what its table says and how far the evidence carries your decision.

Len P. van der Hof5 November 2026

AI Systems

## [MCP is not USB-C: where the favourite analogy breaks, and why that matters](https://lenvanderhof.com/en/blog/mcp-is-not-usb-c/)

The plug is standard. What the model reads through it is not.

Len P. van der Hof6 October 2026

AI Systems

## [MCP OAuth is not tool authorization: a valid token is not a yes](https://lenvanderhof.com/en/blog/mcp-oauth-is-not-tool-authorization/)

OAuth tells your server the token is genuine and meant for it. Your code decides whether this call may approve this expense.

Len P. van der Hof5 October 2026

AI Systems

## [MCP vs function calling: two layers of the same tool call](https://lenvanderhof.com/en/blog/mcp-vs-function-calling/)

In most MCP setups the model still makes a function call. MCP changes where the tool lives, not how the model asks for it.

Len P. van der Hof25 September 2026

AI Systems

## [What is ReasonKit? Structured decisions through MCP](https://lenvanderhof.com/en/blog/what-is-reasonkit/)

An AI assistant can sound certain. ReasonKit makes it show which claims were checked, and stop when the evidence is missing.

Len P. van der Hof4 October 2026