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 bar is lower. The description adds genuinely useful behavioral context beyond that: prices are collected and verified daily, ranking is by review count, and pagePrice follows the same rule as the website/app.

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?

The core purpose and ranking/pricing behavior are front-loaded, which is good. The Korean sentence largely restates the English content, making roughly half the description redundant from a structural standpoint, though it may serve bilingual users.

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 carries the return-shape burden and does so adequately: it explains that sellers are ranked by reviews and that the cheapest price (pagePrice) is returned. Country examples and default types round it out; only explicit sibling routing 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 the baseline is 3. The description earns above baseline by clarifying that 'daily' means N GB/day and 'total' means N GB total, explaining how the type and gb parameters interact, and confirming the 1-30 day trip-length bound.

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+resource+scope: it returns verified daily eSIM/physical SIM prices for a destination country and trip length, ranked by reviews. An agent can clearly tell it apart from trend/comparison/profile siblings by the resource. It stops short of naming which sibling to prefer, so 4 rather than 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?

The description sets context (Korean travelers, Naver SmartStore, 1-30 day trips) and lists the default plan types, implying when the tool applies. However, it never states when NOT to use it or names the alternatives (compare_countries, get_price_trend, get_seller_profile, list_countries), leaving routing to inference.

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