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

Goes well beyond the annotations by disclosing auth requirements (claimed credential with billing write scope) and a concrete failure mode: sandbox keys from self-registration get a 403 until a person claims the workspace. Annotations already cover the safety profile (non-read-only, non-destructive, non-idempotent), so the remaining gap is that retry/idempotency consequences (a repeat call creates a second payment) are never stated.

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 action and its primary parameters, then the non-charging clarification, then prerequisites. It is efficient overall, though restating the status enum and the USD default duplicates schema content and costs a few words.

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 7-parameter mutation tool with no output schema, it covers the essentials: what is created, what is optional, defaults, authorization, and the workspace-claim precondition. It stops short of describing what the created record returns and what happens on duplicate submissions, which would fully close the loop.

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 every parameter is already documented, including defaults for currency and status and the enum. The description restates the same parameter list and defaults with no additional syntax or format guidance, which is the baseline case rather than added value.

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 against a customer") and immediately distinguishes the operation from charging money: "it records the payment in Last Price; it does not charge anyone." This separates it cleanly from siblings like refund_payment, create_invoice, and list_payments.

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?

Makes the use case explicit (bookkeeping a payment against a customer, optionally tied to an invoice) and states a key exclusion ("does not charge anyone"). It does not explicitly name an alternative tool such as refund_payment or create_invoice, so routing for edge cases is left partly to inference.

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