docs(mcp): add comprehensive Hermes MCP docs

Expand the MCP feature docs with filtering and capability-aware registration details, add a practical 'Use MCP with Hermes' tutorial, add a config reference page, and wire the new docs into the sidebar and landing page.

website/docs/reference/faq.md

@@ -391,21 +391,28 @@ mcp_servers:
 
 #### Tools not showing up from MCP server
 
-**Cause:** Server started but tool discovery failed, or tools are filtered out.
+**Cause:** Server started but tool discovery failed, tools were filtered out by config, or the server does not support the MCP capability you expected.
 
 **Solution:**
 - Check gateway/agent logs for MCP connection errors
 - Ensure the server responds to the `tools/list` RPC method
-- Restart the agent — MCP tools are discovered at startup
+- Review any `tools.include`, `tools.exclude`, `tools.resources`, `tools.prompts`, or `enabled` settings under that server
+- Remember that resource/prompt utility tools are only registered when the session actually supports those capabilities
+- Use `/reload-mcp` after changing config
 
 ```bash
 # Verify MCP servers are configured
-hermes config show | grep -A 5 mcp_servers
+hermes config show | grep -A 12 mcp_servers
 
-# Restart hermes to re-discover tools
+# Restart Hermes or reload MCP after config changes
 hermes chat
 ```
 
+See also:
+- [MCP (Model Context Protocol)](/docs/user-guide/features/mcp)
+- [Use MCP with Hermes](/docs/guides/use-mcp-with-hermes)
+- [MCP Config Reference](/docs/reference/mcp-config-reference)
+
 #### MCP timeout errors
 
 **Cause:** The MCP server is taking too long to respond, or it crashed during execution.