billy_get_invoice

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

No annotations are provided, so the description carries the full burden for behavioral disclosure. The description only restates the tool's basic action and does not mention return format, error behavior, permissions, or the impact of the 'include' parameter, leaving significant behavioral aspects undisclosed.

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 a single, focused sentence that immediately conveys the tool's purpose. It is appropriately sized for the tool's simplicity and contains no filler.

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 there is no output schema, the description should explain what the tool returns or any relevant behavioral context. It does neither, leaving the agent to guess about the response shape, error handling, or how 'include' affects the result. The description is minimal but insufficiently informative for a complete understanding.

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%: both 'id' and 'include' have descriptions, with 'include' providing an example. The description text adds no additional semantic value beyond what the schema already provides, so the baseline score of 3 is appropriate.

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 'Get a specific invoice by ID' uses a specific verb ('Get') and resource ('invoice') with a clear scope (by ID). This clearly distinguishes it from sibling tools like billy_list_invoices, which list invoices without an ID filter.

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 tool's purpose is straightforward and implies usage when a specific invoice ID is known. However, it does not explicitly state when to use this over alternatives (e.g., listing invoices) or mention any prerequisites or exclusions.

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