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

Goes well beyond the readOnly/openWorld/idempotent annotations by disclosing latency (5-15 s first call), caching window (10 min), the full status vocabulary, a critical caveat ('Never present manual/unknown results as available'), and that available domains include a registration link. This is unusually rich operational context.

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?

Dense and front-loaded: capability first, then timing/caching, then status semantics, then the sibling-routing rule. Every sentence carries operational information an agent needs; none is 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?

With no output schema, the description still conveys the response shape (status values, registration links) and the safety-critical interpretation rule. Nothing material for correct invocation 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 coverage is 100%, so the baseline is 3, but the description earns extra credit by explaining what the scoping actually covers (domain TLDs, social networks, creative/dev, e-commerce, freelance, gaming, registries), which maps partially onto the categories enum and lets an agent reason about narrowing results.

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 and resource ('Checks whether a name/handle is available on 70+ platforms at once') and enumerates the concrete platform classes covered. An agent can distinguish this from check_domains and suggest_names purely from the description.

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?

Explicit routing guidance: 'to compare many name ideas, first use check_domains (up to 10 names per call), then check_name only on the shortlist.' It names the alternative and the condition that selects it, which is exactly what an agent needs for tool selection.

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