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

With no annotations, the description must disclose behavioral traits. It states 'No browser is launched,' which is a useful non-destructive hint, but it doesn't mention whether network requests are made, side effects, rate limits, or what happens on failure. The schema hints at input discarding, but the description itself is silent on these critical details.

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 description is a single, efficient sentence with no wasted words. It is front-loaded with the core purpose and includes a key behavioral caveat. Perfectly concise, though it sacrifices completeness.

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?

This is a 9-parameter tool with no annotations and no output schema. The description is far too brief to explain what happens with the other parameters, what the return value looks like, or when to use it. It is grossly inadequate for an agent to correctly invoke this tool.

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%, so the baseline is 3, but the description adds no value in clarifying which of the 9 parameters is central. It accepts a url, city, feed, json, path, zone, query, etc., but the description only mentions URL checking, leaving confusion about the purpose of the other parameters. The description fails to tie parameters to the tool's purpose.

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 specific verb ('check') and resource ('URL'), and clarifies that no browser is launched, which distinguishes it from browser-url-ok. However, it doesn't specify the exact method (HTTP status, DNS, reachability) or differentiate from other URL-checking siblings like fetch-status or web-fetch, leaving ambiguity about what 'can be opened' means.

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?

No guidance is provided on when to use this tool versus alternatives. There is no mention of conditions, exclusions, or references to sibling tools. An agent must infer from the name and description alone, which is insufficient.

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