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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the description doesn't need to cover safety. It adds meaningful context by detailing the aggregate return contents (counts, cheapest plan, per-GB price, networks) — valuable since no output schema exists — though it doesn't mention what happens for an unknown country.

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?

One sentence with no wasted words, and the overview framing is front-loaded ahead of the field list. It is slightly dense but every clause maps to real output content.

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 full annotation coverage, the description's enumeration of return fields fills the main gap an agent would have. Only minor omissions remain, such as behavior for unsupported countries or output structure.

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?

There is a single parameter with 100% schema description coverage, including accepted formats (English name, ISO code, alias). The description adds nothing about the parameter, so the schema does all the work — the baseline 3 for high-coverage single-param tools 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 names the resource (eSIM market for a country) and enumerates exactly what the response contains: plan/provider counts, cheapest plan, cheapest per GB, and network lists. This lets an agent distinguish it from plan-level siblings like get_plan or search_plans, though it never explicitly contrasts with them.

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?

"A destination at a glance" implies the overview use case, so an agent can infer this is the right first stop for a country-level summary. However, there is no explicit when-to-use vs. the sibling tools (compare_plans, search_plans, list_providers) and no stated prerequisites or exclusions.

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