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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description adds real content beyond that: it enumerates what each package record contains (data volume, validity, speed, EUR price with VAT, daily plans, monthly pool, networks) and notes the returned page URL, which is exactly the kind of payload context annotations cannot convey.

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 dense sentence that front-loads the purpose and then lists the payload fields; nothing is wasted, though the enumerated field list runs long and 'the monthly pool' is vague phrasing.

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, single-parameter listing tool with full annotation coverage and no output schema, the description covers purpose and returned content well. Minor gap: it does not say whether results are paginated or how an invalid/unknown country is surfaced.

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% and the single country parameter is fully documented with format examples ('tr', 'TH', 'United Kingdom'), so the baseline is 3. The description only echoes 'for one country' and adds no syntax or resolution guidance (e.g. that names are accepted, or to use search_countries).

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 ('List the eSIM packages') plus the scope ('for one country'), which is enough to distinguish it from get_package (single retrieval) and search_countries. It never names the siblings explicitly, so it stops short of 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 browse-plans-for-a-country step, but the description gives no explicit when-to-use, no exclusions, and no routing to get_package for details or search_countries to resolve a country id.

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