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

With no annotations, the description must disclose behavior. It only says 'No browser is launched,' which is a useful differentiator, but it doesn't state whether it performs a network request, what it returns, or how it handles the various parameters that are 'discarded' according to schema. This leaves major 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 extremely concise—two short sentences—and front-loads the core purpose and a key behavioral note. This earns high marks for structure, though the brevity sacrifices necessary detail.

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 and many siblings, the description is incomplete. It doesn't specify the return value, which parameter is required for the core check, or how it differs from fetch-status/web-fetch beyond the no-browser note. An agent would struggle to use it correctly.

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%, so parameters are described, but the tool description doesn't explain which parameter is the primary 'URL' to check or how the others factor in. The description adds no semantic value beyond the schema, and the presence of many unrelated parameters (city, feed, zone, query) without explanation in the description is confusing.

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 operation: checking whether a URL can be opened, and explicitly notes no browser is launched, which distinguishes it from browser-url-ok. However, it doesn't clarify what 'opened' means (e.g., HTTP request or just URL validation), and the many unrelated parameters (city, feed, etc.) muddy 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 on when to use this tool vs alternatives like browser-url-ok, fetch-status, or web-fetch. It only mentions what it doesn't do (no browser) but not when to prefer it.

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