Quoting Sean Lynch

Simon Willison · Simon Willison · 2026-06-19

Developer Sean Lynch, quoted by Simon Willison, argues that MCP's primary value over CLI tools is isolating authentication flows outside the agent's context window, and that MCP's ideal form may simply be an API auth gateway.

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Appears in

Simon Willison's AI-Augmented Datasette Ecosystem: Agent, Apps, and Plugins

Extraction

Topics: model-context-protocolagent-architectureauthentication

Claims

MCP's most distinctive capability over skills or CLI tools is keeping auth flows outside the agent's context window.
The auth isolation MCP enables can extend entirely outside the agent harness, not just the context window.
The idealized minimal form of MCP could be purely an authentication gateway for APIs, with no other functionality.

Key quotes

The real valuable capability MCP offers over skills/CLI is isolating the auth flow outside of the agent's context window, and potentially out of the harness completely.

Maybe the idealized form of MCP is just an auth gateway for the API and nothing else. That'd still be a win.