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

With no annotations, the description carries the full burden and does well: it discloses that detection comes from a single page fetch, the rough signature count (~85), the return shape (each item with its category plus a by-category summary), and an unusual but critical cost of $0.002 USDC on Base via x402. It stops short of failure modes, JS-rendering limits, or whether repeated calls are billed each time.

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 filler: the capability and its coverage come first, then the concrete return shape, then the price. Every clause contributes information an agent would otherwise have to guess.

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?

There is no output schema, yet the description compensates by describing the per-signature category field and the by-category summary, and it flags the x402 payment requirement. Only minor gaps remain around input constraints (public URL, JS-heavy pages, error behaviour) for a one-parameter tool.

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% and the single url parameter is already documented as 'Domain or page URL (allbirds.com)'. The description adds no syntactic or format detail beyond what the schema states, so the 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?

The description names the resource (a website's technology stack) and enumerates the exact detection categories: CMS, e-commerce, frameworks, analytics/tag managers, marketing/chat, payments, CDN, hosting, web server, ~85 signatures. This is precise enough to separate it from website_audit, website_history, and web_extract without opening any schema.

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?

Usage is only implied by 'from one fetch of the page' and the enumerated output. There is no explicit statement of when to pick this over the neighbouring website_audit, website_history, or web_extract tools, nor any prerequisite (e.g. site must be publicly reachable).

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