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

Annotations already declare readOnly/idempotent/non-destructive and openWorld, so the safety profile is covered. The description adds genuinely new behavioral detail: the generation strategy (words joined, common prefixes/suffixes, several TLDs), the fact that every candidate is registry-checked, and that only available results with prices come back. It does not say what happens to unavailable candidates or note any rate/timeout limits on the registry lookups.

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, front-loaded with the core pipeline, with the sibling routing deferred to the end where it belongs. The parenthetical about generation strategy is dense but earns its place; nothing is redundant filler.

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?

There is no output schema, so the description must convey the return shape, and it does ('return the available ones with prices'). Combined with full schema coverage on the three parameters and annotations covering safety and open-world behavior, an agent has enough to invoke correctly; only the handling of unavailable candidates remains unstated.

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%, with tlds, limit, and keywords each documented in the schema, so the baseline is 3. The description only loosely paraphrases keywords ('turn a few keywords into...') and adds no syntax, ordering, or interaction detail (e.g., how keyword spacing affects the prefix/suffix generation) beyond what the schema already provides.

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?

Names a specific action chain (generate candidates from keywords, check each against its registry, return available ones with prices) and explicitly routes the user away from the sibling check_availability for their own ideas. An agent can distinguish this from check_name, check_availability, and search_domains_for_sale 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?

Explicitly states the condition that selects the alternative: 'For your own name ideas, use check_availability.' The tool's own trigger (turn a few keywords into candidates) is also stated, so the when-to-use/when-to-use-instead split is unambiguous.

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