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

Annotations already declare readOnly, idempotent, openWorld, non-destructive, so the description earns credit for what they don't cover: results are cached 24h per domain and directory coverage is deliberately excluded for every domain, including the caller's own. What's missing is any note on failure behavior (unreachable domains, invalid input) or whether the target must be a tracked site.

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 deliverable and packed with useful content in three sentences, with no filler. It loses a point for the convoluted clause "Reports NO directory coverage, for any domain, including your own: that needs the account's submission records," whose emphasis is harder to parse than the rest.

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 describe the return values, and it does: a 0-100 score with A-F letter grade plus llms.txt existence at two locations. Combined with the caching note and the explicit scope exclusion, an agent has everything needed to choose and call this tool correctly.

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?

Only one parameter, and the schema already documents it at 100% coverage ("A domain (example.com) or full URL to scan"). The description adds nothing about accepted formats, normalization, or subdomain handling beyond that, so this sits at the baseline for fully-specified single-parameter schemas.

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 concrete verb+resource ("One-call visibility audit for a public website") and enumerates exactly what is produced: a Sellular visibility score (0-100, A-F) and llms.txt presence at root or .well-known. It also distinguishes itself from the sibling check_submission_readiness by name, so an agent can separate it from the other scan/audit tools without opening any schema.

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?

Gives an explicit positive trigger ("Use when asked to audit or size up a site's overall discoverability in one shot") and an explicit negative scope with a named alternative ("Reports NO directory coverage... ask check_submission_readiness instead"). Both the when-to-use and when-not-to-use conditions are stated outright.

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