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

Beyond the readOnly/idempotent annotations, it discloses the data source (Apple Music + Spotify), the time window (this week), the trend vocabulary (new, up, down), and a critical operational caveat: business use is always 'unknown' and the agent must never tell a business a song is cleared. That is exactly the kind of behavioral constraint annotations cannot express.

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?

Front-loaded with the use case, then return shape, then caveat, then exclusions — a logical order with no filler sentences. The long country enumeration and repeated caveat make it dense, but each clause carries information an agent needs.

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 still specifies the return contents (songs, trend direction, business-use marker) and the governing rule. All three parameters are covered, one required, and the tool's limits (country whitelist, unknown business-use) are fully stated.

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%, so the baseline is 3, but the description adds real value the schema lacks: it enumerates the valid country set (which the schema only describes abstractly as 'country name or 2-letter code') and explains that platform changes the business-account rule shown, which is not stated in the platform enum's description.

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 (returns trending songs) and immediately scopes it: this week's Apple Music + Spotify charts for a given country, with trend and business-use flags. It also explicitly distinguishes itself from adjacent concepts ('a music-chart signal, not a count of Reels or TikTok uses') and from royalty-free music selection.

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 an explicit trigger ('when someone wants popular or trending songs to put on a Reel, TikTok or Story'), a concrete example query, the supported-country list, and two exclusions (not royalty-free music, not countries outside the list). An agent can decide to use or not use it without consulting anything else.

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