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

Annotations already cover safety (readOnlyHint, idempotentHint, destructiveHint=false), and the description adds genuinely new behavioral context the annotations cannot: a $0.05 USDC charge per call via x402 on Base, free on errors, and no charge for unreachable sites. It also reveals the operation performs real-browser loads and captures screenshots, hinting at latency, though it never states an expected duration or timeout.

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 billing caveat is front-loaded in brackets and the remainder is a single dense but well-ordered sentence. Every enumerated item is a distinct deliverable rather than filler, though the list is long enough that an agent skimming may lose the core 'full report for one URL' framing.

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, so the description carries the return-value burden and does so thoroughly by enumerating report sections, screenshot resolutions (1280x800 / 390x844 JPEG), and the prioritized fix list. What is missing is operational: expected runtime for a real-browser audit with 50 link checks, and any failure/timeout semantics beyond the billing note.

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 description coverage is 100% and the single url parameter is already fully documented in-schema (public http(s) hostname, private/reserved addresses refused, defaults to https://example.com). The description only reinforces 'one public URL' and the no-charge-if-unreachable rule, so with the schema doing the heavy lifting a baseline 3 is appropriate.

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 concrete deliverable (a full pre-launch report for one public URL) and enumerates exactly what it contains: status code, redirects, meta/OG tags, robots/sitemap, link breakage, screenshots, TTFB, alt text, heading outline, mobile overflow, and a P1-P3 fix list. That distinguishes it in substance from thin siblings like page_metadata or screenshot_url, though it never names free_site_check or website_audit as the cheaper alternative, so the differentiation is implicit rather than explicit.

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 implied by the 'full pre-launch report' framing and the paid-price banner, which signals this is the heavyweight, costly option. However, there is no explicit when-to-use/when-not-to-use statement and no routing to free_site_check or website_audit for a cheaper pass, so the agent must infer the selection rule from price and feature breadth alone.

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