Find cheapest registrar

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

Annotations already cover read-only, idempotent, open-world and non-destructive semantics, so the safety profile is free. The description adds two pieces of genuine context beyond that: ties are returned ('or tied registrars') and the upstream source is TLD-List v1 extension/getCheapestRegistrar. It says nothing about rate limits, auth, or result ordering.

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 with the core purpose front-loaded and no filler. The endpoint reference is arguably implementation detail an agent does not need, but it is short and adds provenance.

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 4-param read-only tool with full annotation coverage and no output schema, the description is adequate to select the tool but thin on invocation detail: registrar identifier format and include/exclude interaction are left to the schema, which documents neither.

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 coverage is 0%, so the description must carry the burden. It does reference all four parameters conceptually (TLD, price type, registrar include/exclude lists), but gives no format for registrar identifiers, no note on how include and exclude interact, and no clarification of the priceType enum values.

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 ('Find the cheapest registrar') plus the scope that defines it ('one TLD and one price type'). An agent can distinguish it from the compare_* siblings by scope, 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?

The phrase 'for one TLD and one price type' implies this is the single-TLD lookup rather than a bulk comparison, which implicitly routes the agent away from compare_registrars/compare_tlds. However, no alternative is named and there is no explicit when-not guidance.

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