All 4 tools lack input schemas entirely (empty {} for all), violating the critical requirement that every tool must have a documented input schema. Descriptions are present but minimal (10-15 chars), below the 20-char floor for meaningful guidance. No parameter descriptions exist. Tools return unstructured strings instead of typed objects. No error recovery guidance. No output schema documentation. This server fails multiple hard scoring rules.

• Add explicit input schemas to all tools. Even if a tool takes no parameters, declare 'input: {"type": "object", "properties": {}, "required": []}' to signal intentional statelessness.
• Expand tool descriptions to 50-200 characters. Example: 'spotify_play: Resume playback on the user's active Spotify device. Requires an active device to be open in Spotify. Returns success or error if no device is available.'
• Return structured JSON objects instead of strings. Example: spotify_current_track should return {"track_name": "...", "artist": "...", "album": "...", "is_playing": true} with documented schema.
• Add error classification and recovery guidance. Example: 'No active devices found. This is user-fixable: open Spotify on a device and try again. Or call spotify_list_devices() to see available options.'
• Document output schemas for all tools. Specify field names, types, and whether results are paginated. Include examples of success and error responses.