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

With no annotations, the description carries the full burden of behavioral disclosure. It only states 'No browser is launched,' which is one minor behavior. It does not reveal whether the tool performs network requests, what it returns, or how it handles the various parameters. This is insufficient for a tool with no safety annotations.

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 concise (one sentence) but lacks structure. It does not front-load key information or provide any hierarchical organization. It is under-specified rather than efficiently concise.

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 parameters, no output schema, and no annotations, the description is severely incomplete. It does not explain what the tool does with the parameters, what the return value looks like, or how to interpret the result. An agent cannot reliably invoke this tool without further investigation.

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?

The schema provides 100% parameter descriptions, so the baseline is 3. The description adds no extra meaning to the parameters. While the schema is clear on individual params, the description does not explain why parameters like 'city', 'feed', or 'zone' are relevant to checking a URL, leaving semantic gaps that the schema alone cannot fill.

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 ('whether a URL can be opened'), which gives a basic purpose. However, it does not clarify what 'opened' means (syntax, reachability, etc.) and fails to differentiate from siblings like normalize-url or fetch-status. The presence of 9 seemingly unrelated parameters further muddies the purpose.

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 its many siblings. It does not mention alternatives, exclusions, or prerequisites. An agent has no idea whether this is for URL format validation, HTTP reachability, or something else.

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