Add docs on multi user skills and personalized tools

Author: mythz

content/docs/extensions/skills.mdx

@@ -179,6 +179,14 @@ my-skill/
 
 **Note:** The `SKILL.md` file cannot be deleted as it's required for every skill.
 
+## Multi User Skills
+
+In multi-user environments with Authentication enabled, users are only able to manage their own skill collection located at `~/.llms/user/<username>/skills` which are only accessible to them. They can also each enable or disable skills independently without affecting others.
+
+They'll still have access to shared global and project-level skills in `.agent/skills/` and `.claude/skills/`, but won't be able to edit or delete them.
+
+<Screenshot src="/img/skills/skills-authenticated-user.webp" />
+
 ## Skill Metadata (SKILL.md)
 
 Every skill requires a `SKILL.md` file with YAML frontmatter:

content/docs/extensions/tools.mdx

@@ -138,6 +138,20 @@ The tools selector allows curating the available tools for each chat session, be
 
 <Screenshot src="/img/llms-tools-top.webp" />
 
+## Personalized Tools in Multi-User Environments
+
+A tool will be able to return user-specific data when used in authenticated multi-user environments by defining an optional `user` parameter, e.g this is used in the built-in `skill` tool to return skills specific to the authenticated user:
+
+```python
+def skill(name: Annotated[str, "skill name"], file: Annotated[str | None, "skill file"] = None, user=None):
+    """Get the content of a skill or a specific file within a skill."""
+    skills = resolve_all_skills(ctx, user=user)
+    return skills.get(name)
+
+ctx.register_tool(skill, group="core_tools")
+```
+
+When a user is authenticated, the `user` parameter is automatically populated with their username allowing the tool to return user-specific data.
 
 ## Core Tools