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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds real value beyond that: it discloses the retrieval method ('as a browser receives them') and a concrete scope limit (only public web servers on ports 80 and 443). It does not mention rate limits or failure behavior, keeping it short of a 5.

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?

Two sentences, front-loaded with the action and the full list of checks, followed by a tightly scoped constraint. The header enumeration is long but each item is substantive rather than filler.

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 must imply what comes back; saying it will 'grade each' header conveys that findings/grades are returned. Combined with the detail enum documented in the schema, an agent has enough to call it correctly, though the exact response shape remains unstated.

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 description coverage is 100%, including the enum meaning for 'detail' and the flexible 'domain' input format, so the schema does the heavy lifting. The description adds no parameter-level guidance beyond that, making the baseline 3 appropriate.

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?

The description names a specific verb ('Read') and resource ('HTTP security headers a domain's homepage sends') and enumerates exactly which headers are graded, so an agent knows precisely what this returns. It stops short of explicitly contrasting itself with siblings like check_ssl or full_domain_report, though the topic makes the boundary reasonably inferrable.

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 context is implied by the enumeration of checked headers and the scope note that 'Only public web servers on ports 80 and 443 are contacted,' which tells the agent when the tool is applicable. However, it never states when to prefer this over check_ssl or full_domain_report, nor any prerequisites or exclusions.

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