navi_url_preview

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

With no annotations provided, the description carries the full burden of disclosure. It discloses key behavioral traits: returns metadata for public URLs, latency range (~300-800ms), and payment method/amount (x402 USDC). It does not mention error handling or rate limits, but for a simple read-only preview tool, the disclosed information is substantial.

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 description is information-dense and front-loaded with the core purpose. It includes relevant details on cost, latency, and alternatives, but the structure is a bit run-on with the parenthetical payment info. All sentences earn their place, though some consolidation would improve clarity.

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?

Given no output schema, the description adequately lists the expected return fields (title, description, image, favicon, site name, canonical URL, language). It also covers cost, latency, and the alternative tool, making it fully sufficient for a simple 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?

The schema already fully documents the only parameter 'url' with the description 'Full URL to preview (http:// or https://)', so the baseline is 3. The description adds 'any public URL' context, which reinforces accessibility but does not introduce new parameter-level meaning.

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 clearly names the tool as a 'Fast link preview extractor' and specifies exactly what it returns: OpenGraph/Twitter Card metadata (title, description, image, favicon, site name, canonical URL, language). It distinguishes itself from sibling tools by emphasizing speed and low cost for quick scanning.

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?

The description explicitly states when to use: 'Perfect for agents that need to scan many links quickly before deciding which ones deserve deep analysis via /api/web-intelligence'. It also provides a cost comparison and names the alternative (deep analysis), making the distinction clear.

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