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

With no annotations, the description carries the full burden. It usefully discloses the key behavioral trait of not launching a browser, but it does not say whether a network request is made, what inputs are accepted, or what happens on success or failure.

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, front-loaded, with no filler. Every word earns its place and the core behavior is stated first.

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?

Despite the concise opening, the tool is complex with 7 heterogeneous parameters, no annotations, and no output schema. The description leaves core semantics undefined: the agent cannot tell why non-URL parameters exist, what 'can be opened' means, or what the return value is.

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 seven properties have descriptions in the schema, so parameter coverage is high and the baseline is 3. The description adds no parameter detail, and it actually creates a mismatch by focusing only on URL while the schema includes ref, city, json, path, and other heterogeneous parameters, leaving the agent without guidance on how those relate.

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?

States a clear verb ('Check') and resource ('whether a URL can be opened'), and the second sentence distinguishes it from browser-launching tools. However, 'can be opened' is ambiguous (syntax vs. network reachability vs. browser compatibility), and it does not differentiate from normalize-url or domain-shape.

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 description gives no explicit when-to-use guidance or alternatives. 'No browser is launched' hints at a contrast with browser-based tools like playwright-url-ok, but it never names that sibling or states when to prefer this tool. Usage context is only implied.

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