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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral detail beyond annotations: the returned verdict values, trustScore range, riskFlags, evidence, and the batch limit of 5 domains.

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 description is dense but every sentence earns its place: purpose, checks performed, output contract, and parameter usage are all covered in a compact block. It is front-loaded with the core purpose and avoids filler or repetition of the schema.

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?

Given the tool's complexity and the absence of an output schema, the description does well to explain the verdict scale, trustScore, riskFlags, evidence, and batch behavior. Minor gaps remain, such as behavior when no domain parameter is provided and potential rate limits or network dependencies, but these are not critical for basic invocation.

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 adds value by clarifying the relationship between parameters: company_name is for verifying domain-to-company ownership, and 'domains' is an alternative batch mode that excludes company names. This goes beyond the schema's field-level descriptions.

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 opens with a specific verb and resource: 'Verify a business domain, URL or email domain', then enumerates the concrete checks performed (RDAP age, MX/SPF/DMARC, parked-page detection, Wikidata match, look-alike detection). This makes the tool's function unmistakable even without sibling tools to differentiate from.

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?

There are no sibling tools, so alternatives are not applicable, but the description gives clear usage context: pass company_name for ownership checks and use the 'domains' array for batch verification. It does not explicitly state when not to use the tool, but the input modes and intended use are clear.

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