previous

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

No annotations are provided, so the description carries the full burden. It does not disclose whether this restarts the current track when history is empty, whether it resumes playback if paused, or whether device_id is required to target a specific player.

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?

A single short sentence with zero filler, and the action is front-loaded. Nothing is wasted, though it is too terse to earn a 5 given the gaps elsewhere.

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 one-optional-parameter transport control with no output schema, the minimal description is arguably adequate. However, with no annotations and no disclosure of edge-case behavior, an agent cannot fully predict the call's effect.

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 coverage is 100% and the single optional device_id parameter is documented in the schema ('Optional device ID from get_devices'). The description adds nothing further about targeting, so baseline 3 applies.

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 verb+resource ('go back to the previous track'), which an agent can map cleanly to a transport-control action. It is implicitly the counterpart of the sibling 'next', though it never names or contrasts with it explicitly.

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?

There is no when-to-use guidance, no prerequisites, and no mention of alternatives such as 'next' or 'seek'. The usage is only inferable from the tool name and the word 'previous'.

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