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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is partly covered. The description still adds real value by stating "without fetching external URLs," confirming the tool performs static inspection rather than network access — a behavior an agent would otherwise have to guess.

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 sentence with no filler, front-loading the checked properties and ending with the most decision-relevant constraint (no external fetch). Nothing is wasted.

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 and zero schema description coverage, the description should say what the check returns (boolean verdict, list of findings, error on credential detection) and how allowed_hosts alters the outcome. Those gaps matter for correct invocation, though the tool itself is simple enough that they are not severe.

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 0%, so the description must carry parameter meaning, and it only partly does: "hostname allowlist" hints at the allowed_hosts parameter and "scheme"/"credentials" indicate what the url string is examined for. It never explains the format of url or what allowed_hosts accepts when omitted.

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?

Uses a specific verb ("Check") with a concrete resource and enumerates the three things inspected: scheme, embedded credentials, and hostname allowlist. An agent knows exactly what class of analysis this performs, though it does not explicitly differentiate itself from the many sibling utilities.

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 only implied: the checks listed suggest it belongs before dereferencing or trusting a URL. There is no explicit statement of when to prefer this over doing the check inline, nor any exclusion or prerequisite.

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