control_playback

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds important context about the skip behavior limitation ('will only skip once per call'), which isn't obvious from the schema alone. However, it doesn't disclose other behavioral traits like whether this requires authentication, rate limits, what happens if no device is specified, or error conditions. The description doesn't contradict any annotations since none exist.

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?

The description is perfectly concise - two sentences that each earn their place. The first sentence states the core purpose, the second adds crucial behavioral context about skip limitations. No wasted words, front-loaded with the essential information. The structure is logical and efficient.

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?

For a playback control tool with 3 parameters, 100% schema coverage, but no annotations or output schema, the description is minimally adequate. It covers the basic purpose and one important behavioral constraint, but doesn't address authentication needs, error handling, what happens when no device is specified, or return values. Given the complexity of media playback control, more context would be helpful for an agent to use this tool effectively.

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 description coverage is 100%, so the schema already documents all parameters thoroughly. The description adds minimal value beyond the schema - it mentions the same actions and volume control but doesn't provide additional semantic context. The note about skip behavior relates to parameter usage but doesn't add meaning to the parameters themselves. With high schema coverage, baseline 3 is appropriate.

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?

The description clearly states the tool's purpose: 'Control Spotify playback (play, pause, skip, volume)' - a specific verb (control) and resource (Spotify playback). It distinguishes itself from siblings like play_album or play_track by focusing on playback control rather than content selection. However, it doesn't explicitly contrast with all relevant siblings like set_sleep_timer or get_current_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?

The description provides implied usage guidance through the note about skip behavior ('skip-next and skip-previous will only skip once per call'), which suggests when to use this tool versus making multiple calls. However, it doesn't explicitly state when to use this versus alternatives like play_track for starting playback or set_sleep_timer for timed control. No explicit exclusions or comparisons with sibling tools are provided.

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