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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds behavior beyond them: it surfaces alternatives when the name is taken and discloses the slugification rule applied to input, though it says nothing about rate limits or whether the check reserves the name.

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 dense sentences with no waste: the usage directive and sibling reference come first, followed by a concrete normalization example. Every clause carries information an agent would otherwise have to guess.

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 single-parameter, read-only check with an output schema and rich annotations, the description covers the remaining gaps: when to call it, how the input is normalized, and what happens on a taken name. Nothing needed to invoke it correctly is missing.

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 100%, so a 3 is the baseline; the description goes beyond it by explaining normalization semantics — "Bella Roma" becomes "bella-roma" — which tells the agent how raw user input is transformed before lookup. Format details like the 80-char max stay in the schema.

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 (check) and resource (a site name at https://<name>.ginta.page) and implicitly contrasts with the create_site sibling. The agent can immediately tell this is a pre-flight availability check rather than a mutation.

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?

"Use before create_site when the user wants a specific address" gives an explicit trigger condition and correct sequencing relative to the sibling write tool. It does not state an explicit negative case (e.g., skip this if no custom address is wanted), so it falls short of the strongest tier.

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