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

The description discloses that no browser is launched, a useful trait, but it does not explain what actually happens: whether it performs an HTTP request, validates URL format, or checks DNS. It also omits details on network access, timeouts, or what 'opened' means. Parameter descriptions further obscure behavior, e.g., 'path' says 'File path to check; no disk access,' which is contradictory.

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 sentence, which is concise, but it omits critical information about how to use the tool, which parameters matter, and what the result looks like. Conciseness without completeness is under-specification, not efficiency; the sentence fails to earn its place by providing actionable guidance.

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?

With nine parameters, none required, no output schema, and no annotations, the description must explain what the tool does and what to pass. It does not. It fails to specify which parameters are relevant for a URL check, the expected input format, or what the output indicates. This is completely inadequate for an agent to invoke the tool correctly.

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?

All nine parameters have descriptions (100% schema coverage), but the descriptions are largely irrelevant or misleading. For instance, 'ref' is 'Git ref name; discarded after the shape check' and 'city' is 'City name for a public weather hint' – neither relates to checking a URL. These descriptions actively mislead an agent about which parameters to use and what they do, providing no useful semantic value.

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 intent: 'Check whether a URL can be opened.' However, the input schema introduces nine unrelated parameters (e.g., 'city', 'zone', 'query') with descriptions like 'City name for a public weather hint,' which conflict with the stated purpose and confuse the resource being operated on. The name 'playwright-url-ok' implies browser automation, yet the description says 'No browser is launched,' adding further ambiguity about the tool's actual role.

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 instead of siblings like 'browser-url-ok' or 'normalize-url'. The only hint is 'No browser is launched,' which might imply a lighter check, but there is no explicit mention of alternatives, prerequisites, or conditions that would select this tool.

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