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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the exact field set returned, a tier gate that changes what data is available, and a cost of 2 credits — but says nothing about invalid/unreachable URLs, redirect handling, or rate limits.

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 cost note is front-loaded and earns its place, but the opening repeats the tool name twice ("Metadata Extractor: Metadata Extractor is a website metadata extraction API"), which is pure waste. Efficient overall, but not tight.

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?

An output schema exists, so return values need not be spelled out, and the read-only/open-world annotations cover the safety dimension. What remains missing for a single-URL fetch tool — failure behavior on bad URLs and tier-gated field availability per plan — is minor but keeps it below a 5.

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?

With a single parameter at 100% schema description coverage and an example value, the schema already does the work; baseline for high coverage is 3. The description's phrase "any submitted URL" adds only the mild clarification that arbitrary public pages are accepted, not format or constraint detail beyond the 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?

Specific verb and resource: "pulls HTML meta tags from any submitted URL", with the exact fields returned (title, meta description, author, robots directives, language) enumerated. It stops short of differentiating itself from overlapping siblings such as URLTitle, SEODataScraper, or WebsiteTechStackDetector, so it is clear but not fully disambiguating.

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?

There is no when-to-use / when-not-to-use guidance and no alternative named, despite many sibling tools that also take a URL and return page-derived data. The only contextual hint is that paid tiers unlock Open Graph/JSON-LD/favicon data, which is a product-tier note rather than routing guidance.

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