This server suffers from pervasive missing input schemas and absent parameter descriptions on the majority of tools. Of 19 tools, only 3 (list_library, list_playlists, list_playlist) have visible input schemas with parameter descriptions. The remaining 16 tools (add_tracks, remove_tracks, remove_all_tracks, move_tracks, set_active_playlist, set_playing_playlist, set_playback_state, play_at_index, set_focus, create_playlist, rename_playlist, delete_playlist, set_volume, toggle_mute, get_volume, list_current_track) expose only empty input objects {} with no visible parameter definitions, violating the core requirement that every parameter must have a type and description. Tool descriptions exist for some high-level tools but are missing entirely for 14 tools, and where present (list_library, list_playlists, list_playlist), they are adequate. The resource system (current_track_resource.cpp) shows proper implementation with URI-based subscriptions and change notification, but tool-level schema definitions are critically incomplete. No output schemas are documented. Error handling in safe_main_thread_call.h shows exception conversion to mcp_exceptions with generic messages ('internal_error', 'Unknown error'), providing no recovery guidance to LLMs. Tools that perform destructive operations (remove_tracks, remove_all_tracks, delete_playlist) lack any dry-run, confirmation, or permission-gate pattern.

• Add comprehensive input schemas to all 16 undocumented tools (add_tracks, remove_tracks, etc.). Each schema must include parameter names, types (string/number/boolean/array), descriptions, and required/optional flags. Example: create_playlist should accept 'playlist_name' (string, required), 'autoload' (boolean, optional, default false), 'autosave' (boolean, optional, default true).
• Write descriptions for all 16 undocumented tools. Follow the pattern: WHAT does it do + WHEN to use it + WHAT does it return. Example for add_tracks: 'Add one or more tracks to the active playlist. Call this after list_library to add specific songs. Returns the updated playlist with new track count.'
• Document output schemas for all tools in the tool definition (e.g., in comments or a separate schema registry). Specify return type (object/array), field names, types, and example values. E.g., list_library returns an array of track objects with fields: {path (string), artist (string), title (string), album (string), duration_seconds (number)}.
• Add input validation and error messages. Validate foobar2000 query syntax in list_library and list_playlist; return 'Invalid query syntax: ...' with the specific error. Validate playlist_guid format before calling backend. Return 'Playlist not found: <guid>' instead of a generic 500 error.
• Implement confirmation or dry-run pattern for destructive tools. For remove_tracks, add a 'dry_run' (boolean, default true) parameter; return what would be deleted before actually deleting. Require explicit dry_run=false to execute. For delete_playlist, add a 'force_confirm' parameter requiring the playlist GUID to be repeated as confirmation.

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry