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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered by structured data. The description adds the WOEID-lookup workflow but says nothing about freshness (trends are time-sensitive despite idempotentHint), rate limits, or response shape, so it adds only modest behavioral context.

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 tight sentences: the primary action and scope come first, then the cross-tool routing hint. No filler, nothing repeated from the schema.

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 simple read-only tool with 100% schema coverage, no output schema, and annotations covering safety, the description gives everything needed to call it correctly. It could optionally note that trends are time-sensitive, but nothing blocks correct invocation.

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 description coverage is 100%, so format, max_chars and locationId are already documented, and the baseline is 3. The description only adds two extra example WOEIDs (US, UK) on top of the schema's own '1' for worldwide, which is marginal added meaning for the required parameter.

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 ('Get trending topics') plus the scoping key ('for a location by WOEID'), and contrasts itself with get_trend_locations, which looks up WOEIDs rather than returning trends. An agent can distinguish it from the sibling 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?

Explicitly routes the agent: 'Use get_trend_locations to look up other WOEIDs,' which is a clear alternative for the prerequisite step. It stops short of a full when/when-not framing (no mention of caching, freshness, or rate limits), so it lands just below the top.

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