media_previous

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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false. The description adds no behavioral context beyond the implied action—it does not mention what state changes occur, whether an active player is required, or what happens if no player is available. It does not contradict annotations, but it adds little value.

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 a single concise sentence with no wasted words and is front-loaded with the action. It could be slightly more informative without losing conciseness, but it is structurally 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 simple playback action with full schema coverage and annotations covering safety, the description is minimally adequate. However, it omits useful context such as whether the tool requires an active media player or how the optional 'player' parameter affects behavior.

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?

The schema has 100% description coverage for the single optional 'player' parameter, so the schema already documents it. The description does not mention the parameter, but baseline 3 is appropriate when schema coverage is high.

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?

States a specific action ('Go to the previous track') with a clear verb and resource. It implicitly distinguishes itself from media_next, but does not explicitly name or contrast with sibling tools such as media_seek or media_play_pause.

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?

Provides no guidance on when to use this tool versus alternatives like media_next, media_seek, or media_play_pause. The intended usage is obvious from the name, but the description does not add any context or exclusions.

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