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

Description discloses that the tool updates invoice status based on running total, which is important behavioral information beyond annotations. This adds value as annotations only indicate non-read-only and non-destructive nature.

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?

Two concise sentences with no fluff: first sentence states the core action and examples, second sentence explains the effect. 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?

Given the output schema exists, the description covers purpose, effect, and method types. It could mention prerequisites like invoice not fully paid, but overall is fairly complete for a payment recording tool.

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 covers all parameters with descriptions (100% coverage). The description does not add new meaning beyond what the schema already provides for parameters like note, reference, etc., so baseline 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?

Description clearly states the action (record a manual payment), the target (invoice), and specific payment types (cash, bank transfer, cheque, card terminal). It also notes the effect on invoice status (PARTIAL or PAID), distinguishing it from siblings like mark_invoice_sent or void_invoice.

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?

Description implies usage context for recording payments manually against invoices. It does not explicitly state when not to use or mention alternatives, but the purpose is clear enough to avoid confusion with other invoice-related tools.

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