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

Annotations declare readOnlyHint=false and destructiveHint=false, consistent with a non-destructive mutation, so the safety profile is covered elsewhere. The description adds the crucial id-disambiguation behavior, but says the change affects 'amount, date or account' while the schema exposes eleven optional fields, and it never states whether this is a partial update, whether omitted fields are preserved, or what permissions are needed.

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?

One front-loaded sentence carrying the core scope and disambiguation, plus a short second sentence on affected fields. Very little waste, though the second sentence's partial field list is slightly under-informative for an 11-parameter tool.

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 an all-optional mutation tool with full schema coverage and no output schema, the description supplies the routing and identity information an agent most needs. Remaining gaps (partial-update semantics, FX/currency interaction with exchangerate) are minor given the rich schema.

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 baseline is 3, but the description adds real value by clarifying that the id parameter means the payment id on update (the schema text itself is ambiguous, mixing document-on-create and payment-on-update semantics). It does not otherwise enrich the remaining parameters.

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 ('Correct a payment ALREADY recorded against a document') and pins down the identity of the target ('payment id, not the document id'). It also names the sibling it is not (record_document_payment), so an agent can distinguish the two without opening either 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?

Explicitly gives the when-to-use condition (payment already recorded, correct it) and names the alternative with its triggering condition ('to record a new payment, use record_document_payment'). No inference is required to route between the two tools.

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