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

Goes well beyond the readOnly/idempotent annotations by disclosing that data is fetched live every call with no storage, and that a plan-limit message is returned on rate limiting or monthly quota exhaustion — operationally important for an agent's retry logic. It stops short of describing the actual post payload or ordering, so it is very good rather than complete.

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?

Four short sentences, each carrying distinct information: what it returns, freshness semantics, when to pick it, the sibling alternative, and the failure mode. The core scope is stated first with no preamble.

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 conveys the shape at a high level ('top posts' per hashtag/source) and covers the quota failure mode. Slight gap: it does not describe ordering or how results are ranked, nor whether an empty result is possible for an unknown hashtag.

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% and the schema documents all three parameters including the valid source values and the limit default/min/max, so the description correctly defers. It adds nothing extra about parameter behavior, which is the expected baseline here.

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 ('Live top posts') bounded to exactly one hashtag and one source, and explicitly contrasts with the sibling that ranks hashtags instead. An agent can distinguish it from get_top_trends without opening either schema.

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?

'For when the user already has a hashtag and wants the posts winning on it' gives the selecting condition, and 'get_top_trends ranks the hashtags themselves' names the alternative and its own condition. Both sides of the routing decision are explicit.

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