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

Annotations already cover readOnly/idempotent/openWorld, so the bar is lower. The description adds genuine behavioral context: broader indices mix more variety, and playlist-served generation is instant versus a full render. It doesn't discuss any caching or freshness caveats of the pre-baked store, but the safety and cost profile is well conveyed.

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 paragraphs, front-loaded with the purpose, then taxonomy, then the usage preference. Each sentence carries information. Slightly dense but nothing is wasted.

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 an output schema present, return values need not be explained. The description covers the search filter intent, the index taxonomy, and the generate-vs-prompt tradeoff—everything an agent needs to invoke it and act on the result.

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% for the single `search` param, so the baseline is 3. The description adds meaning beyond the schema by explaining the `playlist_index` addressing format used by generate_track and start_stream, which is the whole point of listing these channels—this is useful cross-tool semantics.

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 ('List the music channels'), and goes further by defining the three-level taxonomy addressing scheme. It clearly distinguishes itself from consumers like generate_track and start_stream by naming them as downstream users of the indices it returns.

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?

Explicitly tells the agent when to prefer a playlist over a text prompt ('when the brief maps cleanly onto a genre or mood') and gives the reason (instant pre-baked store vs. full render cost). This is actionable routing guidance, not vague context.

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