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

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses only one trait: no browser is launched. It does not explain whether a network request is made, what 'ok' means, whether redirects are followed, or whether any side effects occur. This is insufficient for a tool with no annotation safety hints.

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 wasted words. The core purpose is front-loaded, and the key behavioral caveat appears immediately after. This is appropriately concise for a simple check tool.

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?

The tool has 9 optional parameters and no output schema, yet the description only mentions URLs. It does not clarify how parameters like city, feed, json, path, or query relate to the stated URL-checking purpose. An agent cannot confidently determine which parameter to supply or what the tool will return.

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 parameters are already documented in the input schema. The description adds no parameter-specific meaning, but the baseline of 3 applies because the schema handles the heavy lifting. The schema descriptions are themselves informative about discarded values.

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 adds a meaningful differentiator with 'No browser is launched,' which helps separate it from browser-based siblings. However, 'can be opened' is slightly ambiguous about whether this is a syntactic check or a network reachability check.

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?

The 'No browser is launched' line implies this is a lighter-weight alternative to browser-based checks, but it never explicitly says when to use this tool versus siblings like browser-url-ok or fetch-status. No alternatives are named and no exclusions are stated, leaving usage context mostly implied.

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