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

Annotations already establish readOnlyHint and openWorldHint. The description adds real behavioural detail beyond that: it discloses the return fields, states the per-call price and billing model, and notes that schema-invalid input is rejected before billing. That is genuinely useful context for an agent deciding to call it.

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 core check and well-sized. There is slight redundancy between the opening sentence and the 'HTTP-to-HTTPS redirect and HSTS status' clause, but otherwise nothing is wasted.

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 responsibly enumerates the returned object fields and documents pricing and input-rejection behaviour. For a single-parameter read-only check, this covers what an agent needs, though it could mention failure/timeout behaviour for unreachable domains.

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 domain parameter, including format and refused suffixes, so the schema does the heavy lifting. The description adds nothing about the parameter beyond what the schema already states, making the baseline 3 correct.

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: checks whether plain HTTP redirects to HTTPS and whether HSTS is set. That is concrete and distinguishable from adjacent tools. It does not name siblings it differs from, though the name makes scope clear.

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?

Usage is implied by the described check but there is no explicit when-to-use guidance or routing against siblings like header-audit, http-status, or cors-check. An agent must infer the selection context.

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