Available Devices

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

Annotations already establish readOnlyHint, openWorldHint, and idempotentHint, so the safety profile is clear. The description adds that the result is a DeviceList and that devices are the user's available ones, which reinforces the open-world nature, but it does not add substantial new behavioral detail beyond what annotations and the output schema already convey.

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 two short sentences with no filler. The core action and resource appear first, followed by a useful return-type note and a direct pointer to the dependent sibling tool.

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 zero-parameter read-only listing tool with annotations covering safety and an output schema present, the description covers the essential purpose and the main downstream action. No critical information is missing.

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 input schema has zero parameters)Skip everything; description cannot add parameter meaning. With no params, the baseline is 4, and the description appropriately avoids fabricating param guidance.

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 uses a specific verb and resource: 'List the user's available Spotify devices.' It clearly differentiates this from the sibling transfer_playback by noting the returned device id can be passed to that tool to make the device active. An agent can immediately understand what this tool does and how it relates to nearby tools.

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 gives a clear practical usage context: call this to see available devices, then use transfer_playback with a returned device id to activate one. It does not explicitly state exclusions or alternatives, but for a simple zero-parameter read tool, the sequential guidance is sufficient.

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