Update payment

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

Discloses much more than the annotations alone: it is a destructive overwrite of the live record, omitting invoice_id unlinks the payment and reopens the invoice balance, it is not idempotent, and a stale SyncToken fails with error 5010. This richly extends the annotation signals without contradicting them.

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?

Three dense sentences cover purpose, use cases, side effects, idempotency, prerequisites, and failure mode with no filler. The primary purpose is front-loaded before the behavioral warnings.

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 a destructive, non-idempotent update with three required parameters and a full output schema, the description covers everything an agent needs: when to use it, what to pass, the overwrite semantics, the token requirement, and the failure behavior. No critical gap remains.

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 100%, so the schema already documents all three parameters and their basic meanings. The description adds valuable behavioral semantics: the payment object is a full replacement, leaving invoice_id out unlinks the payment, and sync_token must come from a fresh get_payment. That raises it above the schema-only baseline.

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 — "Replace the contents of an existing payment" — and gives concrete correction use cases (amount, date, invoice linkage). This clearly distinguishes it from create, get, list, search, and delete payment siblings.

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 frames when to use it: "Use it to correct an amount, a date, or the invoice a payment was applied to." It also communicates the prerequisite of a fresh get_payment SyncToken. It does not explicitly mention alternatives like create_payment for new payments, so it stops short of full when-not guidance.

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