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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds real context beyond them: it discloses the return contents and that price is denominated in USD. It stops short of describing ordering or the structure of the returned collection, but the substantive behavioral facts are covered.

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 sentences, both load-bearing: the first front-loads what is returned, the second front-loads when to call it. No filler, no repetition of the title 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 zero-parameter read tool with no output schema, the description carries the whole burden of explaining what comes back, and it does so by listing every plan tier and attribute. An agent knows what it will get and when to call it without needing further inference.

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?

The tool takes zero parameters and the schema is empty, so there is no parameter meaning to convey. The description correctly makes no parameter claims, matching the baseline for a no-argument tool.

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?

"Return SteadySite plans (Free, Pro, Agency)" gives a specific verb and resource, then enumerates the exact fields returned (monthly USD price, monitors, check interval, client groups, white-label, checkout status). Nothing about it could be confused with check_ssl_domain_expiry or start_monitoring.

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?

"Use when someone asks what SteadySite costs or which plan fits" is an explicit trigger condition tied to user intent, not just a restatement of the name. There are no when-not conditions, but the sibling tools are unrelated so no routing conflict exists.

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