fix: generate skill/slashcommand descriptions synchronously when pre-provided (#1087)

* fix: generate skill/slashcommand tool descriptions synchronously when pre-provided

When skills are passed via options (pre-resolved), build the tool description
synchronously instead of fire-and-forget async. This eliminates the race
condition where the description getter returns the bare prefix before the
async cache-warming microtask completes.

Fixes #1039

* chore: changes by sisyphus-dev-ai

---------

Co-authored-by: sisyphus-dev-ai <sisyphus-dev-ai@users.noreply.github.com>

src/tools/skill/tools.ts

@@ -147,7 +147,14 @@ export function createSkillTool(options: SkillLoadOptions = {}): ToolDefinition
     return cachedDescription
   }
 
-  getDescription()
+  if (options.skills) {
+    const skillInfos = options.skills.map(loadedSkillToInfo)
+    cachedDescription = skillInfos.length === 0
+      ? TOOL_DESCRIPTION_NO_SKILLS
+      : TOOL_DESCRIPTION_PREFIX + formatSkillsXml(skillInfos)
+  } else {
+    getDescription()
+  }
 
   return tool({
     get description() {