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

Annotations already cover readOnly, idempotent, and non-destructive, so safety needs no restating. The description adds genuinely non-obvious operational context: an unauthenticated free tier capped at 10 results versus an API-key tier capped at 30 for 1 credit, which lets the agent reason about cost and result-set size before calling.

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?

Two tightly packed sentences, front-loaded with the core purpose and metric definition, then the tier/cost caveat. No filler and nothing that duplicates the schema or annotations.

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 two-parameter list tool with no output schema, the description should say something about what a returned creator record looks like and over what window 'rising' is measured — neither is covered. The tier and credit information partially offsets this, but key result-shape expectations are left to discovery.

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?

Only the country parameter is documented in the schema (ISO alpha-2 with examples), but the description compensates for the undocumented limit parameter by explaining that 10 is the free ceiling and 30 the authenticated ceiling — directly explaining the schema's maximum of 30. Format details for limit (ordering, whether limit truncates the ranking) remain unstated.

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?

Names the resource (rising creators), the scoping dimension (a country), and defines the ranking metric explicitly as views ÷ subscribers, so the agent knows what 'rising' means here. It does not name a sibling to distinguish from (e.g. rising_keywords, trending_items), leaving the agent to infer the split from the resource noun alone.

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?

Usage is only implied: the country requirement plus the ranking metric suggest 'use this to discover emerging creators in a specific market.' There is no explicit when-to-use or when-not-to-use statement, and no pointer to alternatives like trending_items or analyze_channel for follow-up inspection.

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