get_now_playing

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations provided, so description carries full burden. Describes read operation and edge case. Lacks disclosure of authorization needs, rate limits, or whether an active device is required. Acceptable but not comprehensive.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences: purpose, return fields, edge case. No fluff, front-loaded with key info. Every sentence earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given no output schema, description explains return values and edge case. Could detail data types or nested structure (e.g., artist object) but adequate for simple read. Slight gap in structure detail.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema has zero parameters (100% coverage trivial). Description adds value by describing return structure including the 'is_playing': False case. Baseline 3, plus extra detail gives 4.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Clear verb+resource: 'Get information about the currently playing track'. Distinguishes from sibling tools like search_tracks (searching) and play_track (control). Lists specific returned fields (track name, artist, album, progress, playback state) and handles the edge case of nothing playing.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Implied usage: use to check current playback. No explicit guidance on when not to use or alternatives. Siblings like play_track and pause_playback imply this is a read-only status check, but not stated.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.