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

There are no annotations, so the description must carry the behavioral burden. It does disclose one key behavior ('No browser is launched'), which is valuable. However, it is ambiguous whether 'can be opened' involves a network request or only a shape/syntax check, and it does not mention any side effects, permissions, or output characteristics.

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 the core action and immediately clarifying the important side-effect negation. Every word earns its place; nothing is redundant.

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 description is adequate for a simple check tool, and the schema supplies parameter-level context. But with no annotations and no output schema, the agent is left without information about what the tool returns or how the many parameters relate to the core 'URL can be opened' purpose. Some additional context about intended use would round it out.

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?

The schema descriptions cover all seven parameters, each with meaningful detail (e.g., 'discarded after the shape check'). The overall tool description adds no parameter-specific meaning, but because schema coverage is effectively 100%, a baseline of 3 is appropriate and no compensation is required.

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 action (check whether a URL can be opened) and explicitly notes the absence of a browser launch, which helps distinguish it from a browser-automation tool. It is clear, but it does not explicitly name or contrast sibling checkers to differentiate them further.

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 given about when to use this tool versus alternatives like domain-shape, playwright-url-ok, or normalize-url. The description only says what it does, not under which conditions an agent should choose it.

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