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

Annotations already cover safety (readOnly, idempotent, non-destructive, openWorld), yet the description still adds real behavioral context: no cost, results are live-checked, ranked by price, and restricted to names available right now. It also names the return fields (USD price, checkout_url), so the agent knows exactly what comes back.

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?

Three compact sentences, front-loaded with cost and the primary usage mode, with no filler. Every clause contributes a distinct fact (mode, mechanism, return shape).

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, zero-required, annotation-rich tool with no output schema, the description covers purpose, cost, output fields, and result filtering well. The remaining gap is `max_price` and `tlds` semantics, which an agent would have to guess at.

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 50%: `idea` and `domain` are documented in both schema and description (with concrete examples that clarify intent), but `tlds` and especially `max_price` are unexplained anywhere. "Ranked by price" and "other extensions" hint at those params without defining them, so the description only partially compensates for the coverage gap.

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?

The description states a specific verb and resource ("suggest ... close AVAILABLE alternatives" / "generate brandable names") and enumerates the mechanisms (other extensions, get/try/hq/app variants). It is clearly not the same as search_domains, but it never names a sibling explicitly to make the contrast unambiguous.

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?

"Pass domain ... Or pass idea ..." gives clear guidance for the two entry modes, and the leading "Free." removes a common hesitation about calling it. It stops short of saying when to prefer search_domains or search_aftermarket instead, and leaves the both-empty / neither-passed case unstated.

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