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

Annotations already cover the safety profile (readOnly, openWorld, non-destructive), yet the description adds substantial extra context: it reads vendor blocklists only, cannot distinguish genuine infection from false positive, is free with a personal API token, is limited to 10 fresh scans per hour per token, and caches results for one hour. Rate limits, caching, and the core limitation are exactly the traits annotations cannot convey.

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?

Front-loaded with the action and scope, then triggers, then return shape, then the limitation, then operational limits. Five dense sentences, none of which are filler — the rate limit and caching lines are genuinely load-bearing for invocation planning.

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?

No output schema exists, so the description compensates by describing the return payload (flagging vendor, detection sources, recommended next step). For a single-parameter read tool, nothing needed to call it correctly is missing.

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?

Only one parameter, and the schema description is 100% covered ('Bare domain name... Protocol, www prefix, and path are stripped automatically'). The description adds nothing about the domain argument, so baseline 3 applies.

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 verb and resource ('Check which security vendors are currently flagging a domain') and enumerates the scope (antivirus engines, web blocklists, safe-browsing services). It also carves out what it is not ('does not analyse the site'), which cleanly separates it from the removal-guide sibling.

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?

Gives concrete, trigger-based when-to-use guidance ('browser security warning', 'antivirus blocking their website', 'suspected false positive', 'thinks is blacklisted'), which is unusually actionable. It does not name or defer to a specific alternative tool, so it stops short of a true when-not/alternatives statement.

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