Get a single recurring invoice

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

Annotations already cover the safety profile with readOnlyHint, idempotentHint, and destructiveHint=false. The description adds useful context by noting that the response includes all line items and by showing the exact REST endpoint. It does not disclose error behavior or auth requirements, but annotations lower the burden.

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 short and front-loaded with the core behavior, and the endpoint details are useful. However, the first sentence 'Get a single recurring invoice.' redundantly repeats the title before the more informative follow-up 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?

For a simple single-resource GET with strong annotations and full schema coverage, the description provides enough information: required ID, optional administration, and the endpoint. It could be slightly more complete by explicitly directing collection needs to list_recurring_invoices, but this is not a blocking gap.

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 both parameters are already well documented. The description reinforces that lookup is by ID but adds no meaning beyond the schema, meeting the baseline for schema-covered parameters.

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 a specific action ('Get') on a specific resource ('a single recurring invoice'), further clarified by 'by ID, including all line items.' This distinguishes it from sibling tools like list_recurring_invoices, which operate on collections, and update/create variants.

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 description makes the usage context clear: use this when you need one recurring invoice identified by its ID. It does not explicitly name alternatives or exclusion cases, but the 'single... by ID' phrasing strongly implies the appropriate condition and separates it from list-oriented tools.

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