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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and open-world, so the safety profile is covered. The description usefully discloses the computation basis (first-year price plus current renewal price), but says nothing about data freshness, currency, or the shape of the result.

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?

One sentence, front-loaded with the verb and resource, no filler or redundant restatement of the name. Every clause contributes scope, horizon, or computation basis.

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, read-only calculation with annotations covering safety and no output schema, the description is nearly sufficient but leaves the TLD input and the 'by registrar' output framing ambiguous. An agent has enough to attempt a call but not enough to predict the result structure.

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 0%, so the description must carry parameter meaning. It does enumerate the accepted 'years' values (1, 3, 5, 10) absent from the schema, which is real added value, but 'tld' is never explained, and the phrase 'by registrar' conflicts slightly with a schema that takes a TLD.

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 (calculate) and resource (domain ownership costs) with explicit scope: 1/3/5/10-year horizons, by registrar, derived from first-year and renewal prices. It is distinguishable from siblings like check_domain_prices, though it never names an alternative. Clear but not sibling-differentiating.

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?

The multi-year projection framing implies the scenario (estimating total ownership cost over time), which is more than pure silence. However, there is no explicit when-to-use, when-not-to-use, or pointer to compare_registrar_prices / compare_transfer_savings, which an agent choosing among four price-related siblings would need.

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