Mark Invoice Paid

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

Annotations indicate readOnlyHint=false and destructiveHint=false, confirming it's a write operation. The description adds significant transparency by detailing side effects: updates amount_paid, amount_due, status only when balance reaches zero, and updates client payment_history. It also specifies the return value (confirmation with paid amount and remaining balance). No contradiction with annotations.

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 three sentences, front-loaded with the core purpose, followed by behavioral details and side effects. Every sentence adds value without redundancy or extraneous information.

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 medium complexity (3 parameters, no output schema, side effects), the description covers essential behavior, side effects, and return value. It could mention validation (e.g., invoice must exist and not be fully paid) but overall is adequate.

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 describes each parameter. The description reiterates that amount is optional for full balance settlement, but adds little beyond the schema. It integrates parameters into the tool's flow but doesn't provide new details per parameter.

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 tool's purpose: 'Record a full or partial payment against an invoice.' It details the specific verbs and resources (updates amount_paid, amount_due, sets status conditionally) and distinguishes itself from sibling tools like invoice_create, invoice_list, and invoice_remind by focusing on payment recording.

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 does not explicitly state when to use this tool versus alternatives. While it describes the primary function and side effects, it lacks guidance on when not to use it (e.g., if payment already recorded) or references to alternative actions (e.g., invoice_create for new invoices).

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