> Modern harnesses don't do that, MCP is also progressive disclosure now.

Last time I checked, and it may be different now, Claude Code used tool search only if context usage was greater than 10%.

Also, even with tool search, MCP uses about 1000 to 3000 tokens. A skill frontmatter on the other hand can be around 50.

And an mcp tool call result gets dumped into context in its entirety. A cli too can be filtered with grep/sed etc.

Skills are just a lot more efficient for most use cases.