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 states 'No browser is launched,' which is a single behavioral trait. It does not disclose what happens with each of the nine parameters, what the tool actually does (aside from checking), what the output looks like, or any side effects. This is insufficient for a tool with no annotations.

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 (one sentence), but it is under-specified, not appropriately concise. Critical information about parameters, usage, and behavior is missing. The brevity fails to be 'front-loaded' with useful content because it contains almost nothing beyond the basic purpose.

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?

This is a complex tool with 9 optional parameters, no annotations, no output schema, and many sibling tools. The description provides only a minimal purpose statement and one behavioral note. It is completely inadequate for an agent to correctly select and invoke this tool, especially given the diverse parameters that appear unrelated to the stated purpose.

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 each parameter has a description. The tool description does not add any additional meaning about parameters, which is acceptable since the schema already covers them. However, the parameter set is diverse (url, city, feed, json, path, zone, query, etc.) while the description only mentions checking a URL, creating a mismatch that could confuse an agent. Since the schema is complete, this is a baseline score of 3.

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 verb and resource: 'Check whether a URL can be opened.' It also notes 'No browser is launched,' which hints at a non-browser-based check. However, the meaning of 'can be opened' is ambiguous (syntactic, network, or content check?), and it does not distinguish from siblings like browser-url-ok or fetch-status, which likely perform similar checks.

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?

There is no guidance on when to use this tool versus alternatives. The description provides zero context about scenarios, prerequisites, or exclusions. No sibling tools are mentioned, and no conditions are stated for selecting this tool over others.

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