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

The description discloses one key behavioral trait (no browser launch) but does not mention other aspects such as side effects, network usage, or error behavior. With no annotations provided, the description carries the full burden, and it only partially covers this dimension.

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, consisting of two short sentences. It avoids unnecessary words and conveys the core purpose and a key constraint without padding. This is exemplary in terms of conciseness.

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 simplicity of the tool (checking URL openness) and the complete schema parameter descriptions, the description is sufficient for basic understanding. It lacks details about return values or edge cases, but for a simple check tool this is adequate. A score of 4 reflects that it is nearly complete but could include a bit more context.

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 schema descriptions already cover all 9 parameters (100% coverage), so the tool description adds no additional parameter meaning. Per the guidelines, a baseline of 3 is appropriate when schema coverage is high and the description does not enrich parameter semantics.

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 clearly states the tool's purpose: 'Check whether a URL can be opened.' It also explicitly notes 'No browser is launched,' which distinguishes it from browser-based tools. This makes the purpose unambiguous and easy to understand.

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 hints at usage by stating that no browser is launched, implying a lightweight check. However, it does not explicitly mention when to use this tool versus alternatives like normalize-url or fetch-status. The guidance is implied but not explicit.

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