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

With no annotations, the description carries the full disclosure burden and meets it impressively. It reveals the 10-hop cap, refusal to follow redirects into private address space, per-hop reporting behavior, and the exact $0.005 USDC cost via x402 on Base — non-obvious traits an agent needs before invoking.

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?

Three dense sentences, each earning its place: the first lists outputs, the second gives the use case, and the third covers safety limits and cost. There is no filler or redundant restatement of schema fields.

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 tool with no output schema and no annotations, the description is self-sufficient. It explains the operation, describes the return data, states safety limitations, and provides cost information. Minor ambiguities such as exact behavior beyond 10 hops do not affect the caller's ability to invoke it 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?

The schema already documents the single url parameter with a clear description and example ('a shortened or tracked link'), so coverage is 100%. The description reinforces acceptable input types but adds no new format, syntax, or constraint beyond what the schema already provides, keeping this at the 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 names a specific action — follow a URL's redirect chain one hop at a time — and the resource (URL). It enumerates concrete deliverables: every intermediate host and status, final destination, host-crossing flag, and tracking-stripped copy, which makes the tool's role unmistakable even alongside siblings like url_headers.

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?

It explicitly states when to use it: 'Use before following or showing a shortened, tracked or unfamiliar link.' This is clear triggering context, though it does not name alternative tools or state when not to use it, so it stops short of full routing guidance.

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