mcp_search also points to built-in tools and their availability

Models looked for generate_3d with mcp_search, which only searched MCP
servers, and concluded it did not exist (the chat had been in plan mode, then
switched to build). The search now lists matching built-in tools first:
"available – call it directly" or "not in the read-only mode plan – ask the
user to switch to build mode".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -3,6 +3,15 @@
 All notable changes to CodeCraft. Versions follow [Semantic Versioning](https://semver.org/);
 until 1.0, minor versions may contain breaking changes.
 
+## [Unreleased]
+
+### Fixed
+
+- **Models did not find built-in tools via `mcp_search`** (e.g. `generate_3d` in a chat that
+  had just been switched from plan to build): the search only looked at MCP servers. It now also
+  lists matching built-in tools and says whether the current mode has them ("available – call it
+  directly", or "not in the read-only mode plan – ask the user to switch to build").
+
 ## [v202611-00024] – 2026-11-12
 
 ### Added