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

With no annotations, the description must carry behavioral disclosure. It reveals one useful trait—no browser is launched—but omits the underlying mechanism (HTTP request, DNS check, URL shape only), side effects, network behavior, rate limits, or what is returned. This is thin for safe invocation.

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 no filler; the main action and the key caveat are front-loaded. It is more under-specified than verbose, but conciseness itself is strong.

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?

Given 9 parameters, no output schema, no annotations, and many related URL tools, the description is incomplete. It doesn't say what result the caller receives, which params drive the check, or how this tool differs from the close sibling browser-url-ok. An agent would still have substantial uncertainty.

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%, so the parameters are already documented. The description adds no extra parameter meaning beyond naming 'URL' as the subject. This meets the baseline but provides no bonus value.

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 action and resource: 'Check whether a URL can be opened.' The caveat 'No browser is launched' adds useful distinction from browser-oriented tools. It doesn't define what 'opened' means, but the core purpose is identifiable.

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?

Provides no guidance on when to use this tool versus sibling tools like browser-url-ok, fetch-status, or web-fetch. The no-browser hint implies a constraint, but no explicit when-to-use or when-not-to-use conditions are given.

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