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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so safety is covered. The description adds genuine context beyond that by disclosing the shape of the return payload (variants, fillable field names, live preview URL) and that results are localized via lang, which matters since there is no output schema.

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 sentences with no filler, and the payoff (what you get) is front-loaded before the follow-up routing sentence. Slightly dense but every clause 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?

For a read-only, zero-required-param list tool with no output schema, the description covers purpose, return contents, and the natural follow-up call. Nothing essential is missing; only minor items like whether results are cached or paginated are unaddressed, and those are unlikely to matter here.

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% and the single lang parameter is fully documented with its enum and default in the schema itself. The description references lang only as a token passed to create_site, adding no format or behavior detail beyond what the schema already provides, so the baseline of 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?

States a specific verb and resource ('Lists ready-made Hostilo site designs') and enumerates exactly what comes back: slug, name, description, variants, fillable fields, and a preview URL. That level of detail clearly separates it from siblings like list_sites or get_site, which deal with user-created sites rather than templates.

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?

Explicitly names the downstream action and the parameters it feeds: 'Use create_site with template, template_variant, template_fields and lang to create a site from one.' This gives the agent a clear reason to call it, though it doesn't state exclusions against alternatives (e.g., when a user wants existing sites instead, use list_sites).

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