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

With no annotations provided, the description carries the burden. It does disclose one important trait—'No browser is launched'—which signals a non-browser-based check. However, it omits other potential behaviors such as network requests, whether the URL is actually fetched, or how discarded parameters are handled, leaving 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?

Two short sentences with no unnecessary words. The core action is front-loaded and the behavioral caveat is placed right after, making it easy for an agent to quickly grasp the intent.

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 (8 parameters, no output schema, no annotations), the description is far too sparse. It does not explain how parameters like 'city' or 'json' fit into the tool's purpose, nor does it describe return values or side effects. An agent would struggle to use this tool correctly without opening the schema and inferring intent.

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?

All 8 parameters have schema descriptions, so the baseline is 3. But the tool description focuses only on URL checking, while the schema includes unrelated parameters like city, json, ref, and path. This mismatch creates confusion rather than adding meaning; the description fails to explain why these parameters exist or how they relate to the stated 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 uses a specific verb ('Check') and object ('URL'), and adds a key distinguishing detail ('No browser is launched'). However, 'can be opened' is ambiguous—it doesn't clarify whether this checks URL syntax, DNS, HTTP status, or something else—keeping it from a 5.

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 on when to use this tool versus siblings like playwright-url-ok or fetch-status. The 'No browser is launched' hint implies a lightweight check, but it is never stated explicitly as a usage condition or alternative.

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