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

The description provides context by stating it lists 'packages and their usage,' which clarifies the data returned beyond the simple concept of 'packages.' This adds valuable operational context that is not contained within the schema or 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?

The definition is highly concise, using two sentences to convey function, scope, and the specific API endpoint. The sentence flow is logical and efficient.

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 list/read-only operation with a defined output structure (though not explicitly provided here), the description is complete. It clearly states the scope and provides the technical API reference, making it easier for an agent to validate the operation.

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?

Given that schema description coverage is 75% (above the 80% threshold baseline), a score of 3 is appropriate. The description reinforces the purpose of the `customer_ids` parameter by using the word 'optionally,' but does not add technical depth to the schema definitions.

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 specific terminology ('prepaid service packages and their usage') and a clear verb ('List'), effectively defining the resource and its action. It is clear whether the tool retrieves package definitions or package usage data.

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 indicates usage can be 'optionally for given customers,' implying flexibility. However, it fails to provide explicit guidance on when this tool is necessary compared to sibling tools (e.g., a tool that lists package prices vs. a tool that lists package usage).

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