What's new

• wp_update_post_meta — value schema expanded from string-only to any JSON type (string, integer, number, boolean, array, object). Arrays and objects are serialized by WordPress on write and round-trip as PHP arrays on read. Strictly additive — existing string callers see no behavior change.
• wp_add_post_meta — new tool mirroring WP core add_post_meta(). Adds a meta row without overwriting existing values under the same key. unique=true returns created=false cleanly when a row with the key already exists.
• wp_get_terms — new tool listing terms in any registered taxonomy with paginated output. Optional search, hide_empty, parent filters. Complements wp_add_post_terms (which needs integer term IDs) so agents can map term names to IDs on-site.
• Security — the two meta-write tools reject strings that look like PHP-serialized payloads at the schema boundary. Prevents PHP-object-injection primitives via maybe_unserialize(). Callers pass structured data directly; WordPress serializes safely on write.

Tool counts: WordPress core 67 → 69, total 126 → 129.