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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds value beyond them by disclosing the return payload keys and that 'No login required,' which tells the agent it can call this unauthenticated. Minor gap: no latency or rate-limit context for an open-world network call.

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 verb and resource, then contents, return shape, and triggers — every sentence carries information. Slight inefficiency in placing the use-case sentence after the return-shape sentence, which buries the routing signal, and the header list is long but justified.

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 returned fields ({ domain, grade, score, checks[], server }). Combined with the tested-header list, auth note, and trigger cases, an agent has everything needed to select and invoke this correctly.

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?

With a single parameter at 100% schema description coverage, the schema already fully documents 'domain' with an example. The description adds only the framing 'a website's... headers', confirming the domain is the target, but supplies no format details (protocol, subdomain, path handling). 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 ('Check a website's HTTP security headers'), names the output artifact (A-F grade), and enumerates the exact headers tested. That enumeration distinguishes it from siblings like check_ssl or check_blacklist without needing to reference them by name.

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 concrete trigger conditions: 'when someone asks about website security, why their site got a bad security score, how to improve their security headers, or what headers they're missing.' This covers the initiating intents well, though it does not state when to prefer a sibling (e.g. check_ssl for certificate questions) or any excluded case.

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