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

Annotations already declare readOnly/openWorld/idempotent, so the safety profile is covered. The description adds genuine behavioral value beyond that: it discloses the confidence scale (0-1), the evidence sources used (Wikidata, homepage brand match), and that look-alikes are rejected and alternatives/social links returned.

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?

A single front-loaded sentence that states the primary action first, then enumerates return contents. It is dense but every clause carries information; the trailing list of evidence/alternatives is slightly run-on but still earns its place.

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 lookup tool with no output schema, the description covers what comes back (domain, confidence, evidence, alternatives, rejected matches, social links), which is the main thing an agent needs. It does not say what happens on a no-match or low-confidence failure, which is a minor gap.

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 67%, with the schema itself explaining 'company' and 'country'. The description's mention of 'confidence 0-1' gives indirect meaning to the undocumented minConfidence parameter, but adds nothing for the other two. This is the expected baseline when the schema carries most of the load.

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 names a specific verb and resource ('Find the official website domain of one company from its name') plus a scope constraint ('one company'). There are no siblings to differentiate from, and the purpose is unambiguous without opening the 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?

Usage is implied by the title and the tool name, and the description hints that the input can be a name or a domain/URL/email to verify. However, it never states when to reach for this tool versus another resolution path, nor any exclusions or prerequisites.

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