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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds meaningful context about what the computation includes (renewal price hikes, WHOIS privacy fees, ranking output), but says nothing about data freshness, currency handling, or how many registrars 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?

A single dense sentence with the action and scope front-loaded and no filler. Every clause (TCO, registrars, TLD, renewal hikes, privacy fees, savings) carries information.

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 two-parameter calculation tool with fully documented schema and no output schema, the description covers what is computed and over what horizon. Minor gaps remain around data source/freshness and output shape, but nothing essential for calling it correctly is missing.

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 both parameters (tld, years) are already documented in the schema, including the 1-5 range and default. The description's '1-5 year' restates the schema rather than adding new syntax or format guidance, so the baseline 3 applies.

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 rank) plus a precise resource and scope (1-5 year TCO across all registrars for a given TLD), and enumerates the cost components included (renewal hikes, WHOIS privacy fees). An agent can distinguish it from siblings like domain_prices or compare_providers without opening a 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?

The phrase 'showing potential savings' hints at the use case, but there is no explicit when-to-use guidance and no routing to or exclusion of alternatives such as compare_providers or get_best_deals. Usage is implied rather than stated.

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