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

With no annotations, the description must carry the full behavioral burden. It discloses that no browser is launched, but it does not explain what happens with the many other parameters in the schema, whether the check is read-only, what the return format is, or how the 'discarded' parameters affect behavior. The description also implies a URL-focused tool while the schema includes unrelated parameters, creating ambiguity.

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 extremely concise—two sentences, front-loaded with the primary purpose and a key behavioral caveat. Every word earns its place. It lacks additional structure but remains efficient.

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?

Given the complexity (9 optional parameters, no annotations, no output schema), the description is severely incomplete. It does not explain what the tool returns, how to select the correct parameter for the URL check, what happens with the other parameters, or any side effects. An agent would be unable to call this tool with confidence.

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 coverage is 100% and each parameter has a description, so the baseline is 3. However, the tool description itself does not clarify which parameter is the URL to be checked, and the parameter descriptions (e.g., 'normalize or cite') do not align with the stated purpose of 'opening' a URL. The description adds no value beyond the schema and actually introduces confusion about the tool's scope.

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 action and resource: 'Check whether a URL can be opened.' It also adds a distinguishing detail ('No browser is launched') that separates it from browser-centric tools. However, it does not explicitly name any sibling alternatives, so it misses a point for full differentiation.

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 provides no guidance on when to use this tool versus alternatives. It does not mention conditions, prerequisites, or exclusions. There is no reference to sibling tools like browser-url-ok or web-fetch, leaving the agent to infer usage.

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