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

Beyond the read-only/non-destructive annotations, it discloses the batch ceiling, the verdict vocabulary (FLAGGED or unknown), the returned counts, and critically the semantics that 'unknown' means nothing is known and the tool 'never reports a link as safe' — preventing an agent from misreading a non-flag as a clean bill of health.

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?

Four sentences, front-loaded with the purpose, and every sentence carries useful content. The 'Provide either url or urls' instruction slightly repeats the earlier 'one URL, or up to 25 URLs' framing, a small redundancy that costs it a point.

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?

With no output schema, the description carries the return-value burden and does so: per-link verdicts with reasons plus checked/flagged/incomplete counts. For a two-parameter read-only checker, nothing an agent needs to call or interpret it 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?

Schema description coverage is 100%, and the schema already documents both parameters including 'Omit when sending url/urls' and maxItems 25, so the baseline is 3. The description largely restates those same constraints rather than adding new parameter semantics.

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 (checks URLs against RelayShield's threat-intelligence corpus for phishing, malware, and scam abuse) and scopes the input shape (one URL or up to 25). The URL-centric scope cleanly distinguishes it from the siblings check_breach, check_email, and check_wallet.

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?

Explicitly tells the agent how to invoke it ('Provide either `url` ... or `urls`'), making the mutual exclusivity of the two parameters clear. It gives no explicit when-not-to-use guidance or routing advice relative to the sibling checkers, but the resource boundary is unambiguous enough that the gap is minor.

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