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

With no annotations, the description carries the burden and does well: it discloses that redirects are followed, which data sources are consulted (RDAP), and the four verdict values (no_signs, mostly_ok, caution, likely_scam). It omits failure behavior (unreachable URL, timeout), latency, and rate limits, so the agent cannot predict edge cases.

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 dense paragraph that front-loads the question and then packs the evidence list and the verdict vocabulary with no filler. The closing scope disclaimer earns its place by preventing misreadings.

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?

Absent an output schema, the description responsibly enumerates the return signals and enum values, which is what an agent needs to interpret results. Residual gaps are error/unreachable handling and confidence/limitations beyond the malware disclaimer.

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; the description adds real value by stating that redirects (including shorteners, per the schema's bit.ly example) are resolved, meaning the input need not be the final destination. It does not discuss malformed URLs or whether bare domains are normalized.

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?

Opens with a specific question ('Is this website legit or a scam?') and enumerates the exact signals returned (RDAP domain age, look-alike brands, risky TLDs, DMARC, HTTPS), which makes it unmistakable against siblings like check_website_status or whois_lookup. It also bounds scope explicitly: 'Warning signs only; not a malware scan.'

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 context is clear from the framing question, and one exclusion is stated ('not a malware scan'), which steers agents away from expecting payload analysis. It does not, however, name an alternative tool or state when a simpler status/DNS check would suffice instead.

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