scan_url

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

With no annotations, the description carries the full burden and does disclose useful behavior: it returns page metadata plus "available security signals," and that deeper analysis is gated by subscription plan — a real operational constraint an agent should know before promising results. It does not say whether the tool actively fetches/renders the target (a safety-relevant trait for a scanning tool) or mention rate limits, leaving some behavioral surface uncovered.

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?

Four short sentences, front-loaded with the core purpose, then usage, then return behavior. No filler, though the phrasing is terse enough that the sibling boundary could have been added at little cost.

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 scan tool with no output schema, the description covers purpose, when to use it, what comes back, and the plan-dependent limitation. The main remaining gap is the absence of any safety/operational note about contacting the target URL, which matters for a security-scanning 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 coverage is 100% and the single parameter already documents itself with an example format. The description adds no extra meaning about the URL parameter, so the schema does the work and baseline 3 applies.

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 ("Deep forensic URL analysis" detecting phishing, malware, redirects), which is more precise than the name alone. It implicitly separates itself from domain-level siblings by emphasizing "specific links, login pages, or suspicious URLs," but never names inspect_domain or check_domain_safety, so the URL-vs-domain boundary is left to inference.

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?

"Use this to verify specific links, login pages, or suspicious URLs" gives a clear positive trigger for invocation. It stops short of explicit exclusions or naming the sibling to use instead when the subject is a whole domain rather than a single URL.

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