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

Beyond annotations (readOnly=false, openWorld=true, destructive=false), the description adds useful behavior: cloud routing, no need for the app to be open, automatic device selection for TV and line-in, and a fallback path for TV. This is meaningful added transparency for a state-changing action.

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, front-loaded with the core function, with cloud behavior and fallback in supporting sentences. Each sentence adds operational information, though the middle sentence packs multiple details.

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 two-parameter action with no output schema, the description covers what the tool does, what source choices mean, cloud dependency, and a fallback. It doesn't describe return values or failure behavior for music/line-in, but these are minor for invocation.

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 only documents room; source has an enum but no description. The description compensates by explaining the source values ('TV audio (soundbar HDMI/optical)', 'line-in') and their device-selection behavior. It does not explicitly map them to parameter names, but the meaning is clear.

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?

Description says 'Switch a room between music, TV audio (soundbar HDMI/optical) and line-in,' naming the exact action and the three source values. This makes it easy to distinguish from volume, playback, and reminder siblings.

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 clear context: switching goes through Sonos cloud so the user needn't be home or have the app open, and TV has an explicit fallback to the ZoneFoundry app on home Wi-Fi. It doesn't explicitly say when not to use it or name an alternative, but the context is sufficient.

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