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

Annotations only declare readOnlyHint=false and openWorldHint=true, so the description usefully adds the auth/pricing model and the shape of the result (0-100 score plus named finding categories). It omits operational traits an agent would want, such as scan duration or whether the call is synchronous, which matters for a non-read-only, open-world scan.

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?

Three dense sentences, action-first, with the outcome and access tier packed into the same breath. No filler beyond the product branding, and nothing that could be dropped without losing information.

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?

No output schema exists, and the description compensates by naming the return values (score plus finding categories) and the entitlement model. For a single-parameter tool this is nearly sufficient, though run time, behavior on unreachable URLs, and rate limits are unaddressed.

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 100% for the single url parameter, so the baseline is 3, but the description adds meaning the schema does not: the URL must point at a deployed (publicly reachable) web app, not local source. That materially narrows what value to pass.

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?

Names a specific verb+resource ('Run a ... security & speed scan') plus what it produces (0-100 score, findings like exposed secrets, missing RLS, frontend leaks, speed). The 'deployed web app URL' scope cleanly separates it from the local-code sibling scan_local_code and from the narrow check_* tools.

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 clear context on the target case ('deployed web app URL', 'Best for apps built with Lovable, Bolt, v0, Cursor, Replit') and the access tier (Pro with entitled API key, otherwise free). It never explicitly says when to prefer this over check_security_headers or check_ssl, so the alternative routing is left to inference.

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