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 only reveals that no browser is launched, but omits critical behaviors: what the tool actually does with the non-URL parameters (e.g., 'city', 'feed', 'json'), what the return value looks like, and whether any side effects occur. The discrepancy between the description (URL-only) and the schema (nine heterogeneous parameters) is unexplained, making the tool's behavior opaque.

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), which is good, but it lacks structure. It front-loads the core purpose but does not introduce the broader context that the schema implies. There is no mention of the other parameter groups or the possibility that the tool performs multiple checks. The conciseness comes at the cost of completeness, so it earns a mid-range score.

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 parameters, no output schema, and no annotations. The description is extremely thin for this complexity. It does not explain the roles of the many parameters, does not describe the output format, and does not provide usage context. An agent would be unable to correctly invoke this tool for anything beyond a simple URL check, and even then it is unclear how to supply the URL parameter. This is a severe gap.

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 the baseline is 3. The schema descriptions are individually informative (e.g., 'discarded after the shape check'), but the tool description adds no extra meaning about how parameters relate to the core function. The presence of unrelated parameters (city, feed, json, zone) without explanation in the description reduces the value of the schema, as the agent cannot map parameters to the stated 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 clearly states the primary purpose: 'Check whether a URL can be opened.' It also adds a useful behavioral note ('No browser is launched.'). However, it does not differentiate from sibling tools like 'playwright-url-ok' or 'fetch-status', which likely serve similar purposes. The mismatch between the stated purpose and the extensive input schema (including 'city', 'feed', 'json', etc.) introduces ambiguity about the actual scope.

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 such as 'playwright-url-ok' or 'normalize-url'. The description gives no context about selection criteria, prerequisites, or scenarios where this tool is preferred. An agent has to infer usage from the name and description alone, which is insufficient given the large sibling set.

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