books_get_invoices

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

The schema includes readOnlyHint and idempotentHint, which already inform the agent that this is a safe, read-only, idempotent operation. The description adds little behavioral context beyond that, mentioning filtering and pagination (already in params) and use cases. It does not contradict the annotations, so the score is at baseline with annotations present.

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 concise sentences plus a related-tools line. It front-loads the primary purpose, adds use cases, and then points to related tools. Every sentence contributes value with no fluff.

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/retrieval tool with strong schema annotations, the description covers purpose, use cases, and key capabilities. It lacks explicit mention of the return format (no output schema exists), but 'Get invoices' implies it returns invoice objects. The related tools section helps orient the agent among many siblings. Slight gap: no mention of default sort or result limits beyond parameters.

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% for all 8 parameters, so the schema provides full meaning for each filter and pagination option. The description adds no new parameter-level detail, but the generic mention of 'filtering and pagination' reinforces the overall intent. Baseline of 3 is appropriate given the high schema coverage.

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 states a specific verb ('Get'), resource ('invoices from Books'), and scope ('with filtering and pagination'). It also lists concrete use cases ('find invoices for payments, get invoice details, or browse invoice history') which helps distinguish it from other tools. The plural 'invoices' and mention of pagination clearly differentiate it from the singular 'books_get_invoice' tool in the sibling list.

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 provides clear usage context ('Use to find invoices for payments, get invoice details, or browse invoice history') and explicitly names related tools with their purposes (create, pay, customer details). However, it does not contrast with the closely related 'books_get_invoice' (singular) tool, so the guidance could be more precise about when to choose this listing tool over the single-invoice retrieval tool.

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