Fix taxonomy tools for taxonomies whose rest_base differs from slug

CLAUDE.md

@@ -216,6 +216,15 @@ All taxonomy operations use a single `taxonomy` parameter:
 }
 ```
 
+The `taxonomy` parameter accepts either the taxonomy slug or its `rest_base`
+(custom taxonomies can register a rest_base that differs from the slug, e.g.
+slug `documentation_category` with rest_base `documentation-categories`).
+All taxonomy tools resolve the identifier through a per-site cached
+`/wp/v2/taxonomies` lookup and hard-error on unknown taxonomies — there is no
+slug fallback. `assign_terms_to_content` derives success from the WordPress
+response (the updated content's `rest_base` field must contain the requested
+term IDs) rather than echoing the request.
+
 #### Multi-Site Support
 All tools accept an optional `site_id` parameter to target specific sites:
 ```json

README.md

@@ -207,6 +207,13 @@ All taxonomy operations use a single `taxonomy` parameter:
 }
 ```
 
+The `taxonomy` parameter accepts either the taxonomy slug or its `rest_base`
+(they can differ for custom taxonomies, e.g. slug `documentation_category`
+with rest_base `documentation-categories`). Tools resolve the identifier via
+`/wp/v2/taxonomies` and error on unknown taxonomies instead of guessing.
+`assign_terms_to_content` verifies the write against the WordPress response
+and reports an error if the terms were not actually saved.
+
 ## Configuration
 
 ### Single Site Configuration

src/tools/unified-content.ts

@@ -93,7 +93,8 @@ async function getPostTypes(forceRefresh = false, siteId?: string) {
 }
 
 // Helper function to get the correct endpoint for a content type
-async function getContentEndpoint(contentType: string, siteId?: string): Promise<string> {
+// Exported for reuse by unified-taxonomies.ts (assign_terms_to_content / get_content_terms)
+export async function getContentEndpoint(contentType: string, siteId?: string): Promise<string> {
   // Quick return for standard types
   const standardMap: Record<string, string> = {
     'post': 'posts',