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

With no annotations, the description carries the full burden and does so well: it enumerates the exact warning signals returned, discloses operational limits (max 10 hops, 60 s cache), and states the scope exclusion for malware scanning. An agent knows what it gets back, how deep it goes, and how fresh the result is before calling.

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?

Front-loaded with a purpose question, then dense but relevant detail on outputs, warnings, and limits. No filler sentences, though the parenthetical enumeration of redirect types and warning signals is long enough to slow scanning slightly.

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?

For a one-parameter, non-destructive read tool with no output schema, the description fully specifies inputs, returned fields (chain, status codes, final URL, title, warnings, tracking-stripped URL), and boundaries. Nothing an agent needs to call it correctly is missing.

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% for the single url parameter and the schema already supplies examples. The description reinforces the accepted input shapes (bit.ly-style short links, tracking links) but adds no format or validation detail beyond the schema, so baseline 3 applies.

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?

Specific verb+resource ('follows a URL hop by hop') with an explicit scope statement of what the output contains (each redirect, status codes, final URL, title, warnings). Clearly distinguishable from siblings like whois_lookup or check_website_status, which cover registration and availability rather than the redirect chain.

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?

Gives concrete usage contexts (short links, tracking links, QR code links) and one explicit when-not boundary ('Does not scan pages for malware'). It stops short of naming sibling tools such as whois_lookup or check_website_status as follow-ups for domain or uptime questions, so routing is inferred rather than stated.

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