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

Annotations already declare read-only, idempotent, non-destructive, and closed-world. The description adds genuinely new behavior: the return includes a Call link opening the Suparelay browser dialer and that this tool 'does not dial' — an important scope limit not derivable from annotations.

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?

Four short sentences, front-loaded with what is returned and followed by usage and a scope caveat. Every sentence carries information, though the closing browser-dialer remark slightly overlaps the earlier 'Call link' sentence.

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 compensates by explaining the return payload (landline/mobile prices per minute and a Call link) and clarifying that the tool itself does not place the call. An agent has everything needed to invoke and interpret it.

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?

One parameter with 100% schema description coverage, so the schema already documents the ISO 3166-1 two-letter code and its example. The description repeats the format guidance ('two-letter ISO country code, such as IN') without adding anything new, so baseline 3 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?

States a specific verb and resource: returns landline and mobile per-minute prices plus a Call link for a given country. The clause 'without a phone number' functionally separates it from the sibling get_call_price, which presumably takes a number, though the sibling is not named.

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?

Explicitly says when to use it: 'when the person wants to call a country or asks what calls to it cost, without a phone number.' This is a clear usage condition, but it does not name the alternative tool or state when to prefer get_call_price instead.

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