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

Goes well beyond the readOnlyHint/openWorldHint annotations by disclosing fallback behavior (DNS fallback for RDAP), how unsupported platforms surface (could_not_confirm plus manual links), per-check UTC timestamps, and the 'not legal advice; nothing is registered' caveat. This tells the agent exactly how to interpret uncertain or partial results, which the annotations alone cannot.

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?

The trigger is front-loaded and the dense middle sentence packs the source list with zero filler. It is somewhat run-on, piling platforms, fallbacks and legal caveats into one long clause, but no sentence is wasted.

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 carries the burden of describing returns and does so: serial, registration number and status for trademarks, per-check timestamps, could_not_confirm flags, and the Markdown table structure. For a six-parameter, multi-source tool this is complete.

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 already 100%, so the baseline is 3, but the description adds cost and limit context the schema does not: the '1-3 names' cap and 'optional free variations and Markdown report' framing tells the agent variations cost nothing and reports are optional. It does not restate defaults for tlds/tm, leaving those to the schema, which is appropriate.

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 trigger and scope ('Use before naming a product, company or project') and enumerates the exact resources checked: RDAP domain availability, handles on named platforms, Apple App Store apps, and USPTO trademarks. An agent can distinguish this multi-source brand screen from siblings like domain_dns or site_audit without opening any 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?

The opening sentence gives a clear situational trigger (pre-naming) that establishes when to reach for this rather than a single-purpose lookup. It does not explicitly name alternatives among the siblings or state exclusions, so it stops short of full routing guidance.

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