compare_sites

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

Annotations already provide readOnlyHint: true, so the description does not need to disclose read-only behavior. The description adds no additional behavioral traits beyond what annotations convey, such as rate limits or scope limitations, so it meets the baseline with annotations present.

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 consists of two concise sentences with no fluff. The first sentence directly states the function, and the second adds context for usage. Every word earns its place.

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?

Given that the tool has only one well-documented parameter and an output schema exists, the description is complete enough. It clarifies the comparison scope (SEO, performance, and security) and aligns with the tool's purpose, leaving no obvious gaps.

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?

The input schema has 100% description coverage for the single 'urls' parameter, so the schema already provides clear semantics (comma-separated URLs, example). The tool description does not add extra meaning beyond the schema, resulting in a baseline score of 3.

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 clearly states the tool compares SEO and performance scores of multiple websites side by side. It uses a specific verb ('compare') and resource ('scores'), and distinguishes itself from sibling tools like seo_audit and performance_audit by focusing on side-by-side comparison rather than single-site auditing.

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?

The description explicitly says 'Useful for competitive analysis — see how your site stacks up against competitors', providing clear context for when to use the tool. However, it does not explicitly mention when not to use it or suggest alternative tools, which prevents a perfect score.

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