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

Annotations already indicate read-only, idempotent, non-destructive behavior. The description adds safety validation and clarifies that JavaScript is not executed and access controls are not bypassed, providing behavioral context beyond annotations.

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 concise with three sentences, each adding value: first states core purpose, second gives constraints, third provides parameter guidance. No wasted words.

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 tool's simplicity (2 params, no nested objects), output schema exists, and annotations are complete, the description adequately covers all necessary context for an agent to use the tool correctly.

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 covers both parameters with detailed descriptions (e.g., url includes SSRF rejection). The description reiterates parameter usage (absolute URL, fresh default) but adds minor contextual advice on when to set fresh=true, which is slightly beyond schema.

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 returns the safely validated redirect chain for public HTTP(S) resources. It distinguishes from sibling tools like web.url.status or web.url.headers by specifying redirect chain validation, and mentions it does not execute JavaScript or bypass access controls.

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?

Explicitly states usage for public HTTP(S) resources only, warns against private or SSRF-sensitive URLs, and provides clear guidance on the fresh parameter (cache reuse vs. new fetch). This helps the agent decide when and how to use the tool.

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