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

With no annotations provided, the description carries the full burden. It discloses what the score measures (meta tags, sitemap, llms.txt, structured data) and the output grade, which is useful. However, it does not explain behavior for invalid URLs, non-public sites, rate limits, or whether it is a fast lookup versus a live scan.

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 concise sentences front-load the action and result, include the scoring scale and measurement signals, and end with a usage directive. Every sentence contributes meaning with no redundancy.

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 one-parameter tool with no output schema, the description covers the key facts: input, output range, grading, measured signals, and typical use case. It does not describe the exact response shape, but that is less critical given the simple nature of the tool.

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 schema already fully documents the single parameter (url) with a clear description of domain or full URL. The tool description adds no new parameter semantics beyond restating 'domain or URL,' so the 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?

The description names a specific resource (Sellular visibility score), a concrete output (0-100, A-F), and the input type (domain or URL). It is clear and distinct from the sibling tools by focusing on the visibility score rather than a full scan or audit summary, though it does not explicitly reference a sibling to differentiate.

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 states when to use the tool: 'Use when asked how discoverable or SEO-ready a site is.' It provides clear context for the agent, but does not mention exclusions or alternatives such as seo_audit_summary or compare_visibility, leaving some routing ambiguity.

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