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

Annotations already mark it read-only and non-destructive, and the description adds meaningful behavioral context: it presents credits, recommended badge, and labels, and forbids quoting USD or backend provider names. This goes beyond a generic 'list' statement, though it does not cover error/empty-state behavior.

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 description is compact and front-loaded with the precondition, then the action, then the display constraints. Every sentence adds necessary information, with no fluff or repetition of the title.

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?

Given the simple 2-parameter schema, read-only annotations, and presence of an output schema, the description covers prerequisites, scope, and display constraints completely. Nothing essential for selecting or invoking the tool 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?

With 0% schema description coverage, the description compensates by identifying 'service' as the serviceCode and clarifying that 'country' is a numeric id from summary/detail. It gives provenance and type for both parameters, though it could be even more explicit about the exact value format of service.

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 uses a specific verb and resource ('list credit-priced routes') and clearly scopes the tool to the post-selection package-picker step. The 'credit-priced routes only' and 'never quote USD or backend provider names' constraints distinguish it from broader pricing/rental siblings like ucode_sms_prices and ucode_sms_rent_with_credits.

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?

It states the precondition 'After user picks serviceCode + country (numeric id from summary/detail)', which tells an agent when to invoke it. It does not explicitly name alternatives or say when not to use it, but the context is clear enough to avoid confusing it with rental-execution or general pricing tools.

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