It's funny you mention this - for a while I was concerned that CC wasn't fetching the appropriate documentation related to the task at hand (coincidentally this was around Aug/Sept when Claude had some serious degradation issues [1]), so I started adding the following to the beginning of each specialized doc file:

  When this documentation is read, please output "** LOGGING DOCS READ **" to the console.

These days I do find that the TOC approach works pretty well though I'll probably swap them over to Skills to see if the official equivalent works better.

[1] https://www.anthropic.com/engineering/a-postmortem-of-three-...