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

Goes well beyond the annotations by disclosing that an accounting entry is created, that the payment is added to the bank account/gateway collections list, that partial payments are allowed, and that a confirmation step applies by default. It also flags the prerequisite of the user's Cotlet API key, which is exactly the kind of operational context annotations don't carry.

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?

Front-loaded with the core action and side effects. The second sentence largely repeats the first ('Records one payment... with an amount, a date and a payment method'), and the confirmation/API-key notes add bulk, but the content is generally useful and well-ordered.

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?

With no output schema, the description usefully notes that the response exposes what is left open on the invoice, and it covers side effects, partial-payment behavior, and auth. This is nearly complete, though the 'open in the response' phrasing is vague about the exact return shape.

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 all four parameters are already documented in the schema. The description only restates that a payment has 'an amount, a date and a payment method' without adding format, currency, or validation detail, so baseline 3 applies.

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?

States a specific verb and resource ('Record a payment received on an invoice') and immediately scopes it as 'in full or in part'. It also names the side effects (accounting entry, payments/collections list), so an agent can distinguish this from sibling invoice-creation or listing tools without opening the schema.

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?

Clear context for when to use it (a payment has been received) and clarifies that unlimited partial payments are supported. It does not name any alternative tool to prefer instead, so it lacks the explicit when-not/alternative routing that would earn a 5.

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