record_payment

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

Annotations already declare this is a non-read-only, non-destructive, closed-world write, so the safety profile is covered. The description adds one genuinely useful behavioral rule — overpayments are rejected — but says nothing about partial payments, duplicate submissions, idempotency, whether the invoice status changes, or what error is raised on refusal.

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 short sentences, front-loaded with the action and followed by the most important constraint. Nothing is padded or redundant.

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?

An output schema exists, so return values need not be explained, and annotations cover the write/read profile. However, for a financial mutation tool the description omits material behavior: how partial payments interact with the invoice, what happens on repeat submission, and what the refusal condition actually is beyond 'overpayment'.

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 coverage is only 60% (reference and invoice_number have no descriptions), so the description should compensate, and it does not — it mentions no parameter at all. The overpayment rule implicitly constrains 'amount' relative to the invoice balance but never states that relationship explicitly.

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 and resource ('Record money received against an invoice'), which is immediately actionable. No sibling tool records payments, so there is little to disambiguate, though it never explicitly differentiates itself from adjacent tools like get_document or list_invoices.

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?

There is no when-to-use or when-not-to-use guidance, no mention of prerequisites such as the invoice needing to exist or be in a particular status, and no alternatives named. The only constraint given ('Overpayments are refused') is a rejection rule, not usage guidance.

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