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

Goes well beyond the readOnly/idempotent annotations by disclosing that summary, movers and droppedApps always describe the full top 200 regardless of `limit`, that movement is empty on the first day a chart is requested, and that no API key is needed but free-tier daily use per IP is rate-limited.

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-loads what the tool returns, then usage, then the two caveats an agent could get wrong. Every sentence carries distinct information with no filler.

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 compensates by enumerating the return shape (per-app rank delta, new apps, biggest movers, dropped apps) plus the limit/aggregate caveat, making it complete enough to call correctly.

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 semantics the schema lacks: the exact truncation behavior of `limit` versus the full-200 aggregates, and the day-over-day delta semantics tied to chart requests.

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 with scope modifiers ('store top chart (free / paid / grossing, overall or by category) with day-over-day movement'), which cleanly separates it from siblings like sonar_app_rankings and sonar_app_overview.

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?

Gives an explicit use case ('Use to see what's rising in a market or category'), which tells the agent the right context. It does not, however, name or exclude a sibling alternative for chart-adjacent queries.

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