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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive. The description goes beyond by stating 'no scan triggered, no network call from this tool, no auth'—adding operational details about side effects and network behavior. It also specifies the output is a JSON with badgeUrl, which is useful behavioral information not present in annotations.

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?

The description is concise, front-loads the core purpose, and each sentence adds value: it states the action, notes side effects, lists styles, and mentions an alternative. No fluff or redundancy. Structure is logical: purpose, safety, output, style options, usage guidance.

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 simple 2-param tool with no output schema, the description covers everything: purpose, behavior (no network call), output format, style enum meaning, use case, and alternative tool. It fully compensates for the lack of an output schema and leaves no ambiguity for the agent.

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 50%: domain has a description, style has enum/default. The description adds the style options ('flat, flat-square, plastic, large') and clarifies domain input ('Domain name only, e.g. example.com (no URL, path, or port)') which reinforces the schema description. It also implies the purpose of the style parameter by mentioning it's for badges. However, it doesn't explain how the badge URL is constructed (e.g., what the URL looks like), but the schema handles most semantics. Since coverage is 50%, the description partially compensates, but it could add a bit more detail on the style parameter's effect.

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 states exactly what the tool does: 'Build the direct SVG badge URL for a domain's security score.' It specifies the verb (build), the resource (direct SVG badge URL), and clarifies it's pure URL construction with no side effects. It also distinguishes itself from the sibling tool get_pdf_report_link by naming the alternative.

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?

Explicitly tells when to use: 'Use for embeddable status badges' and explicitly contrasts with get_pdf_report_link for a downloadable full report. The description also clarifies that it's for README, GitHub, status pages, or wikis, giving clear context. No other alternatives are needed since the sibling list is extensive but only that one is relevant.

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