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

Goes well beyond the annotations (which only cover read-only/idempotent/open-world safety) by disclosing the cost model (free, no x402 challenge), the absence of side effects (no render, no charge), and the exact shape of the response including the fingerprint that binds the quote to the URL. This is precisely the behavioral context annotations cannot convey.

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-loaded with the key fact (free preflight) and the return contents, which is good. However, the free/no-charge message is repeated three times ('FREE,' 'no charge,' 'no payment required... this tool is free'), and the HTTP-equivalent line adds length of marginal value to an MCP caller.

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?

For a one-parameter, no-output-schema tool, the description covers return values, cost, and side-effect absence, so an agent can call it confidently. The remaining gap is that the vocabulary of the response ('fence verdict,' 'servability') is never defined, leaving the agent unsure what values to expect.

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 0% — the single `url` parameter has no description. The description partially compensates by noting 'same URL input' as access_scan and that the fingerprint binds the quote to 'this exact URL,' implying the URL is the scan target, but it gives no format, scheme, or normalization guidance.

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 ('FREE preflight for access_scan') and enumerates exactly what comes back: servability, fence verdict, $0.05 toll quote, and request_fingerprint. It is clearly distinguishable from the sibling access_scan and from access_crawl_preflight by naming the parent tool it preflights.

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?

Tells the agent to call it directly without payment ('no x402 challenge; this tool is free') and signals the boundary with access_scan by stating 'no accessibility signal of any kind is returned.' It stops short of explicitly saying 'use access_scan when you need the actual accessibility result,' but the implication is strong and unambiguous.

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