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

Annotations already establish read-only, safe, and idempotent behavior. The description adds a useful behavioral trait beyond those: 'Page content is not stored,' which clarifies privacy/storage semantics. It does not contradict the annotations and provides context about what the tool does not do.

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 filler. The primary behavior is front-loaded, and the second sentence adds a meaningful privacy guarantee. Every word earns its place.

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 has a complex multi-parameter schema (url, city, json, feed, etc.), yet the description only addresses the URL case. Without an output schema, the agent lacks a complete picture of what the tool returns or how the other parameters behave in context. The description is therefore not complete enough for the tool's complexity.

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 seven parameters have individual descriptions in the schema, so the schema coverage is high. The tool description adds no parameter-specific meaning beyond the schema, but the baseline of 3 is appropriate because the schema already carries the explanatory burden.

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 specific, concrete behavior: 'Return host, scheme, and HTTP status for a URL.' This distinguishes it from content-fetching tools like web-fetch. However, it mentions only the URL aspect and ignores the other seven input schema parameters (city, feed, json, etc.), so the purpose is only partly captured.

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 gives no guidance on when to choose this tool over siblings such as normalize-url or fetch-status. The statement 'Page content is not stored' weakly implies it is not for content retrieval, but no alternative is named and no explicit when/when-not rules are provided.

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