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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds useful provenance ('URLhaus + heuristic analysis'), telling the agent results come from an external feed plus local heuristics, but says nothing about verdict fields, confidence, or failure behavior.

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?

Two short sentences with zero padding, and the purpose is front-loaded before the implementation note. Every sentence carries information.

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 is the only place an agent could learn what comes back (a verdict? a score? raw URLhaus records?), and it says nothing about return shape. For a simple read-only one-param tool this is a real but modest 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 100% and the single parameter carries an example, so the schema fully documents it. The description adds no format constraints (scheme required, encoding, max length) beyond the schema; baseline 3 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?

Names a specific verb (check) and resource (URL) plus the threat classes it evaluates, so the agent knows exactly what the tool does. It doesn't explicitly distinguish itself from check_domain or check_ip, which is the only gap.

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 is no statement of when to prefer this over check_domain/check_ip/full_scan, nor any exclusions or prerequisites. The agent must infer from the name alone that the input must be a full URL rather than a bare domain or IP.

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