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

With no annotations, the description must disclose behavior, but it only reveals that no browser is launched and that some parameters are 'discarded.' It does not state what happens to the URL (whether it's fetched, syntactically checked, etc.), what the tool returns, or side effects. The 'discarded' notes are partial and inconsistent (e.g., url, host, path, zone have no such note).

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?

The main description is concise and front-loaded with the purpose and key constraint (no browser). It avoids unnecessary words. However, it is under-specified overall, which is a completeness issue rather than a conciseness flaw.

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?

For a tool with 9 optional parameters, no required fields, no output schema, and no annotations, the description is severely incomplete. It does not explain the role of most parameters, what the tool returns, error conditions, or when to use it. An agent would be unable to call it correctly for anything beyond a simple URL check.

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 each parameter is documented in the schema. The description adds a small amount of value by noting which parameters are discarded (ref, city, json, query), but it does not add meaning beyond the schema for the core parameters like url, host, or path. Baseline of 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?

The description states a clear verb and resource: 'Check whether a URL can be opened.' It also distinguishes from sibling 'browser-url-ok' by noting 'No browser is launched.' However, the presence of many unrelated parameters (city, json, path, zone, etc.) creates ambiguity about the tool's actual scope, so it's not a 5.

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 guidance on when to use this tool versus alternatives like browser-url-ok or normalize-url. It does not state conditions, prerequisites, or exclusions. The only hint is 'No browser is launched,' which implies a lightweight check, but this is not explicitly framed as a usage rule.

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