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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's added value is the important caveats: prices are monthly in KRW and quoted before VAT, and the response comes back in Korean. Those are exactly the details that prevent misinterpretation of the returned numbers. It does not describe breadth of the plan list or any rate/limit behavior, so not a 5.

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 front-loaded sentence that identifies the product, then the returned fields, then the language caveat in six words. Nothing wasted and nothing structural missing.

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 and no parameters, the description carries the burden of describing the return value, and it does so field by field with currency and tax basis clarified. Complete enough to call blind; only the absence of any hint about list size or ordering keeps it at 4.

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 has zero parameters, so the baseline is 4. The description correctly adds no parameter talk and instead spends its words on the shape of the result, which is the right allocation.

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 the exact resource (OnPress subscription plans) and enumerates the returned fields — name, tagline, monthly price in KRW before VAT, first-year price, features — so an agent knows precisely what it gets. No sibling overlap exists among get_guide/how_to_start/list_templates/search_guides, but the description never says so explicitly, which keeps it from a 5.

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?

Usage is only implied: an agent can infer this is the tool for pricing/plan questions, but there is no explicit trigger, no prerequisite, and no statement about when a sibling such as get_guide would be the better choice. Adequate but leaves inference to the caller.

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