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

Annotations only cover the read-only/open-world safety profile, so the description carries the rest: it discloses the paid model ($0.009 USDC per call via x402 on Base/Solana/Polygon/Arbitrum), how payment is handled, and the 7,600+ fingerprint corpus. Pricing and payment mechanics are exactly the kind of behavioral trait an agent must know 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?

Front-loads the core purpose, then returns, then params, then price/sample. Dense but every clause contributes; the detection-surface list borders on verbose but is justified for disambiguation.

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?

With no output schema, the description usefully enumerates return fields (name, categories, version, confidence, evidence, by-category summary), and it covers payment, required input, and a runnable example. An agent has everything needed to call and interpret this 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 description coverage is 0%, so the description must compensate, and it does restate both parameters: url as required and min_confidence with its 0-100 range and default of 50. It stops short of explaining what min_confidence actually thresholds (fingerprint match confidence) or the expected URL format beyond the example.

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?

States a specific verb and resource ('Detect the technologies a website uses') and enumerates the exact detection surfaces (HTML, headers, cookies, meta tags, script URLs) plus the fingerprint source. This clearly separates it from generic page tools like page_extract or seo_meta.

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?

Gives a concrete usage trigger via the free sample input and payment note, implying 'call this to fingerprint a site,' but never states when to choose it over siblings such as seo_meta, site_audit, or page_extract. Usage is implied rather than delineated.

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