docs: improve Gemini CLI documentation and configuration guide

docs/gemini-cli-setup.md

@@ -78,9 +78,36 @@ Install these as skills so they activate only when relevant:
 - `security-and-hardening` — Activates during security reviews
 - `performance-optimization` — Activates during performance work
 
+## Advanced Configuration
+
+### MCP Integration
+
+Many skills in this pack leverage [Model Context Protocol (MCP)](https://modelcontextprotocol.io/) tools to interact with the environment. For example:
+
+- `browser-testing-with-devtools` uses the `chrome-devtools` MCP extension.
+- `performance-optimization` can benefit from performance-related MCP tools.
+
+To enable these, ensure you have the relevant MCP extensions installed in your Gemini CLI configuration (`~/.gemini/config.json`).
+
+### Session Hooks
+
+Gemini CLI supports session lifecycle hooks. You can use these to automatically inject context or run validation scripts at the start of a session.
+
+To replicate the `agent-skills` experience from other tools, you can configure a `SessionStart` hook that reminds you of the available skills or loads a meta-skill.
+
+### Explicit Context Loading
+
+You can explicitly load any skill into your current session by referencing it with the `@` symbol in your prompt:
+
+```markdown
+Use the @skills/test-driven-development/SKILL.md skill to implement this fix.
+```
+
+This is useful when you want to ensure a specific workflow is followed without waiting for auto-discovery.
+
 ## Usage Tips
 
 1. **Prefer skills over GEMINI.md** — Skills activate on demand and keep your context window focused. Only put skills in GEMINI.md if you want them always loaded.
-2. **Skill descriptions matter** — Each SKILL.md has a `description` field in its frontmatter that tells Gemini when to activate it. The descriptions in this repo are already optimized for auto-activation.
+2. **Skill descriptions matter** — Each SKILL.md has a `description` field in its frontmatter that tells agents when to activate it. The descriptions in this repo are optimized for auto-discovery across all supported tools (Claude Code, Gemini CLI, etc.) by clearly stating both *what* the skill does and *when* it should be triggered.
 3. **Use agents for review** — Copy `agents/code-reviewer.md` content when requesting structured code reviews.
 4. **Combine with references** — Reference checklists from `references/` when working on specific quality areas like testing or performance.