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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world scope, so the safety profile is covered. The description adds that results are "published" and "possibly changing", warning the agent that prices are volatile, but it says nothing about pagination, the meaning of the 25-item cap, or freshness/caching.

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?

There is only one sentence and it is front-loaded with the action, so nothing is padded. The semicolon-compressed, comma-heavy clause ("published, possibly changing country/operator prices") borders on ungrammatical and costs more clarity than the brevity saves.

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 three parameters, zero schema descriptions, and no output schema, the description should at minimum explain what `service` selects and what shape the price options take. Neither is present, so an agent must guess both the required input's role and the response 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?

Schema description coverage is 0%, so the description carries the full burden and does not meet it: `service` (required), `limit`, and the slug pattern are unexplained. It mentions country and operator, but "operator" is not even a parameter, which can mislead an agent into expecting to filter by operator.

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 verb "Browse" and resource "country/operator prices and public availability" give a rough sense of a read-only catalog lookup, but the phrasing never states plainly that it returns SMS activation price options for a given service, and it omits the required `service` argument. It is distinguishable from eSIM-oriented siblings only by implication.

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?

"No rental or OTP retrieval" is an explicit when-not-to-use clause, which is real guidance. However, no alternative sibling (e.g. list_sms_services for enumerating services) is named, and there is no positive statement of the situation that should select this tool over the eSIM plan tools.

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