Calculate domain ownership cost

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: it discloses the pricing model, that currencies are never combined, and that assumptions are returned. It does not say what happens for missing price data or how currency is selected.

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, zero filler, with the cost model and the currency constraint front-loaded. Every clause 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 3-parameter read-only calculator with no output schema, the description covers the cost model, the currency constraint, and mentions returned assumptions. It is close to complete, though the return shape beyond 'assumptions' is left vague and no output schema exists to fill that gap.

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 bound 'years' to 1-10 and identifies the registrar/TLD pair, but gives no format guidance for 'tld' (e.g., 'com' vs '.com') or 'registrar' (name vs ID), leaving real ambiguity.

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), resource (domain ownership cost), scope (1-10 years, one registrar/TLD pair), and even the formula (year-1 registration plus subsequent current renewal prices). The 'one registrar/TLD pair' framing implicitly separates it from comparison siblings like compare_registrars and cheapest_registrar, though no sibling is named explicitly.

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?

Usage is only implied by the stated scope: use this for a single registrar/TLD pair rather than a comparison. There is no explicit when-to-use, when-not-to-use, or alternative-tool routing against compare_registrars or cheapest_registrar, which are the obvious neighbors.

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