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

With no annotations, the description must carry the full behavioral burden. It discloses that no browser is launched, which is a useful limitation, but it does not describe side effects, permissions, network behavior, or what happens with the various parameters (many are discarded per schema). The read-only nature is implied but not explicit.

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 sentence, extremely concise and front-loaded. It wastes no words, but it is so brief that it omits critical context. Still, for conciseness, it earns a high score; the structural efficiency is good.

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?

Despite a fully covered schema, the description is too thin for a tool with 9 parameters and no output schema. It does not explain what 'opened' means, how the check is performed, what the return value looks like, or why many parameters are discarded. An agent cannot fully understand the tool's behavior from the description alone.

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% – all nine parameters have descriptions. The tool description adds no additional parameter context, so the baseline of 3 applies. It does not clarify which parameter is primary (likely 'url') or how the discarded parameters interact with the check.

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 function: 'Check whether a URL can be opened' – a specific verb and resource. It also notes 'No browser is launched,' which helps distinguish it from browser-based siblings like 'browser-url-ok'. However, the meaning of 'opened' is ambiguous (HTTP request? DNS check? file path?), and it doesn't explicitly differentiate from other URL tools like 'fetch-status' or 'normalize-url'.

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 alternatives. There is no mention of contexts, exclusions, or comparisons to sibling tools. The description is purely functional and leaves the agent to infer usage from the name or schema.

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