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

With no annotations, the description carries the full burden of behavioral disclosure. It reveals only that no browser is launched, but does not disclose how the URL is checked, whether any network request occurs, what side effects exist, or what the result represents. This is insufficient for a tool with no annotation support.

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 tight sentence with no filler. The 'No browser is launched' clause is valuable and front-loaded as an exclusion. Every word earns its place.

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?

For a tool with 9 optional parameters, no output schema, and no annotations, a one-line description is not enough. It does not explain what 'ok' means, what return value the agent should expect, whether parameters can be combined, or how the tool verifies a URL without a browser. The schema provides param details but the behavioral and output context remains incomplete.

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 the baseline is 3. The description adds no parameter-level meaning and is actually narrower than the schema, mentioning only URLs while the schema also includes city, ref, json, path, zone, query, feed, and host. The schema already documents each parameter, so the description does not need to repeat them, but it also does not clarify how they relate to the stated URL-checking purpose.

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 check ('whether a URL can be opened') and adds a key distinguishing trait ('No browser is launched') that separates it from browser-url-ok. However, 'can be opened' is operationalized nowhere, and the 9-parameter schema suggests broader validation capabilities than just URLs, which muddies the purpose.

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 over siblings like fetch-status, normalize-url, or web-fetch. The phrase 'No browser is launched' implies a lightweight alternative but never explicitly states the intended use case, exclusions, or preferred conditions.

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