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

Annotations already establish it as a safe read (readOnlyHint=true, destructiveHint=false), so the bar is lower, yet the description adds real value: results are in Sonos' stored order, no bridge is required, and favorites are capped near 70 with `total` reflecting the true count. That ~70-vs-total quirk is exactly the kind of behavioral detail an agent cannot infer elsewhere.

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 tight sentences, front-loaded with what is returned, then two short caveats. No filler; each sentence carries distinct operational information.

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?

With no output schema, the description helpfully discloses the returned fields and the approximate 70-item cap plus `total` semantics. It is nearly complete, lacking only pagination/limit interaction detail.

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?

There is a single `limit` parameter whose schema description is fully covered (100%), so the baseline is 3. The description mentions `total` but does not clarify limit behavior or interaction with the cap, adding nothing beyond the schema.

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 and resource ('Lists the home's Sonos favorites') and even enumerates the returned fields, which clearly separates it from siblings like list_playlists or search_music. It does not name an alternative explicitly, so it stops short of a 5.

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?

'Works without the ZoneFoundry bridge' is useful context about when this tool is viable, but there is no explicit guidance on when to prefer it over list_playlists or search_music. Usage is implied rather than scoped.

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