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 only one trait: 'No browser is launched.' It does not state whether a network request is made, what happens on failure (e.g., timeout, 404), whether redirects are followed, or what the return format is. This is far too little for a tool with nine parameters and no output schema.

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 brief – two sentences – which is concise but under-specified. Both sentences earn their place (the core purpose and the no-browser note), but the brevity comes at the cost of necessary detail. It is not verbose, but it is not appropriately sized because it omits critical information an agent needs to call it correctly.

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 is complex with nine parameters, no required fields, no output schema, and no annotations. The description is just two sentences and does not explain what 'open' means, what the tool returns, or how the parameters relate to the purpose. It is severely incomplete; an agent has almost no guidance on when to use it or how to interpret results.

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 has 100% coverage, so the baseline is 3. The description adds no parameter semantics – it does not explain how parameters like 'city', 'zone', 'json', or 'path' relate to the stated purpose of checking a URL. Since the schema already documents each parameter, the description adds zero value beyond that, but the high schema coverage keeps this at baseline.

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 verb and resource ('Check whether a URL can be opened') but the phrase 'can be opened' is ambiguous – it doesn't clarify whether it checks HTTP status, redirects, or content validity. It also does not differentiate from sibling tools like browser-url-ok or fetch-status, which likely have overlapping purposes. The added note 'No browser is launched' gives a hint but does not specify the actual mechanism.

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 provides no guidance on when to use this tool versus alternatives. It does not mention any sibling tools, exclusions, or conditions. The only implicit clue is the name, but that is not sufficient. There is no 'use this when...' or 'not for...' statement.

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