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

With no annotations, the description carries the full burden. It does disclose that page content is not stored, which is a useful behavioral trait. However, it does not state whether a network request is made, whether the operation is read-only, or any error behavior. It implies a safe read but lacks explicit disclosure of side-effects or limitations.

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 sentences, no fluff. The main purpose is front-loaded and the behavioral disclosure follows immediately. Every word serves a purpose, and the text is extremely efficient.

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 description states the return values (host, scheme, HTTP status) and the no-storage policy, which is useful. However, it omits when to use this tool, how it interacts with the other 8 parameters, and what happens on invalid URLs or non-200 responses. Given no output schema, the description should be more complete.

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 description coverage is 100%, so the schema documents all 9 parameters. The description adds no additional meaning beyond the schema; it only mentions 'URL' generically without explaining that only the 'url' parameter is actually used while others are discarded. It doesn't enrich parameter understanding.

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?

Description clearly states the operation: 'Return host, scheme, and HTTP status for a URL' – a specific verb and resource. It also adds a distinguishing detail ('Page content is not stored') that separates it from content-fetching tools like web-fetch. However, it doesn't explicitly name sibling tools or contrast with similar URL-check tools like fetch-status or normalize-url, so it stops short of 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 on when to use this tool versus alternatives. It doesn't mention conditions for choosing citation over fetch-status, normalize-url, or web-fetch, nor does it explain any exclusions or prerequisites. The agent is left to infer usage from the description alone.

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