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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely useful non-annotation context: the data source (watchlist accounts), the freshness boundary ('from the last scan'), and that it is free. It stops short of describing the shape of a breakout alert, but the added operational context is strong.

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?

Three short sentences, front-loaded with the triggering condition, then the data scope, then the negative routing. 'Free.' is a single word that earns its place; there is 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?

For a read-only, single-optional-param list tool whose annotations cover safety, the description supplies everything needed to select and invoke it. The only minor gap is that no output schema exists and the description does not characterize what a returned alert contains (fields, count semantics).

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% for the single 'limit' parameter, including range and default, so the schema carries the semantics. The description adds no interpretation of the limit or what counts as a breakout, which is the expected baseline when the schema is fully documented.

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+resource ('get breakout alerts' plus 'trending keywords') and scopes them to the user's own watchlist accounts and last scan. An agent can distinguish this from xcut_search_viral 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?

Explicit when-to-use ('user asks what is breaking out or trending in their own niche right now') and explicit when-not, naming the alternative and the selecting condition ('topic or creator outside their watchlist -> use xcut_search_viral'). Nothing is left to inference.

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