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

Annotations already declare readOnly, idempotent, closed-world, non-destructive, so the safety profile is covered. The description adds a genuinely non-obvious behavioral detail: when the subdomain is taken, it returns the most similar alternative. It does not discuss how the name is normalized into a subdomain, but the key behavioral outcome is disclosed.

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?

A single compact sentence that front-loads the main outcome (the resulting address) before the availability check and fallback. No redundant wording; the only mild weakness is that everything is packed into one long clause.

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 two-parameter, read-only lookup with full schema coverage and no output schema, the description covers the essential contract: what is computed, whether it is free, and what comes back if it is not. Without an output schema, more detail on the return shape would help, but an agent has enough to call it 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?

Schema description coverage is 100%, so both parameters (name, country) are already documented with meaning, including that country drives currency, language, branding and payment methods. The description refers to 'ese nombre' but adds no new parameter semantics beyond the schema; 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 states a specific verb+resource: it reports which address (subdomain) a store would get with the given name and whether it is available. That is clearly distinguishable from siblings like create_store or preview_store. It stops short of explicitly naming how it differs from preview_store, which is the nearest neighbor.

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 purpose implies a pre-creation availability check (the fallback-alternative behavior makes that clear), but there is no explicit statement of when to use this versus preview_store or create_store, and no prerequisites or exclusions. Usage is inferable rather than stated.

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