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

With no annotations provided, the description carries the full disclosure burden. It reveals one meaningful behavioral constraint: no browser is launched, signaling a non-invasive check. But it does not clarify whether the check is purely syntactic, whether it makes network requests, or what 'can be opened' concretely means, which leaves important behavioral gaps.

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 two short sentences with zero filler. The core action is front-loaded, and the most important constraint, 'No browser is launched,' follows immediately. 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?

The tool has a 9-parameter schema and no output schema, yet the description explains neither what 'can be opened' means nor what the tool returns. The presence of unrelated parameters (city, feed, json, path) is unexplained, and the agent is left to guess the expected input and result format. For a tool with no annotations, this is inadequate.

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 input schema provides descriptions for all 9 string parameters, including notes about being 'discarded after the shape check,' so schema coverage is 100%. The tool description adds nothing about which parameter is the primary one (presumably 'url') or why seemingly unrelated parameters exist, but the schema already does the heavy lifting.

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 and resource: 'Check whether a URL can be opened.' The second sentence, 'No browser is launched,' clearly distinguishes this tool from sibling tools like playwright-url-ok that do launch a browser, so the agent can tell this tool apart without opening schemas.

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 implies this is a lightweight, side-effect-free check by noting 'No browser is launched,' which gives some contextual signal for when to use it. However, it never explicitly names alternative tools or states conditions for choosing this over normalize-url, fetch-status, or playwright-url-ok, leaving selection largely to inference.

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