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

The annotation readOnlyHint=true already indicates this is a safe read operation. The description adds the API endpoint but does not disclose additional behavioral details such as not-found handling or response format. This is acceptable for a simple GET but does not go beyond the annotation's coverage.

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 two short sentences with no wasted words. The core action is front-loaded and the API endpoint is a concise, useful reference. Every sentence earns its place.

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 simple read-only get operation with one required, fully documented parameter and a readOnlyHint annotation, the description is nearly complete. It omits details about return payload or error conditions, but these are not critical for such a straightforward 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?

Schema description coverage is 100%, so the schema already documents invoice_id as 'Chargebee invoice id.' The description mentions 'by id' and includes {invoice_id} in the endpoint, reinforcing the parameter's purpose but not adding meaning beyond the schema.

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 clearly states the action ('Retrieve') and the specific resource ('a single invoice by id'). It is easily distinguished from sibling tools such as chargebee_list_invoices, which retrieves multiple invoices, and chargebee_get_customer, which targets a different resource.

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?

The phrase 'single invoice by id' clearly implies this tool is for fetching one specific invoice when an id is known, in contrast to listing all invoices. However, it does not explicitly state exclusions or name alternative tools for different use cases.

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