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 reveals that no browser is launched, but does not describe what check is performed, whether it sends an HTTP request, what the output/response format is, or any side effects or limitations. This is insufficient for a tool with no annotation support.

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, front-loaded sentence with no filler. It states the core purpose and the key caveat (no browser) efficiently, earning a high score for conciseness.

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 or annotations. The description gives almost no context on how to use it, what the result looks like, or when to invoke it. This is incomplete for a tool with this complexity, leaving agents to infer behavior from the name and schema alone.

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 individually documented in the schema. The description itself adds no parameter information and even focuses on 'URL' while the schema includes many unrelated fields (city, feed, json, path, etc.). The schema carries the meaning, so baseline 3 applies.

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'), and explicitly distinguishes from browser-launching alternatives by noting 'No browser is launched.' This separates it from sibling tools like browser-url-ok, though it does not elaborate on what 'opened' means (e.g., HTTP status).

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 siblings like fetch-status, browser-url-ok, or normalize-url. The only implicit hint is the 'No browser is launched' clause, which suggests it is lighter than browser-url-ok but does not explicitly state selection criteria or exclusions.

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