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

With annotations already declaring readOnlyHint=false, idempotentHint=false, destructiveHint=false and openWorldHint=true, the description adds real value on top: the authority gate, the two possible outputs (Stripe MPP route vs human fallback), and the assurance that payment is never claimed before ledger verification. It stops short of describing failure/retry behavior for a non-idempotent write.

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 tight sentences with the core behavior front-loaded and no filler. The jargon ('Stripe MPP machine-payment route') costs a little clarity but every sentence carries information.

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 non-idempotent, open-world purchase mutation with no output schema and undocumented nested inputs, the description covers outcome and the payment-verification guarantee well but omits error handling, whether an intent can be cancelled, and any detail about what the five required inputs must contain.

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 0% across five required parameters including two nested objects, yet the description only says 'Five-field' and names no field. It does not explain offer_id, task_summary, safe_scope_confirmed, or the purchase_authority structure, so it fails to compensate for the coverage gap; only the schema's own inline hint on maximum_amount helps.

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: it creates one bounded purchase intent for a fixed-scope Zinvyl service and returns a payment route. However, it never distinguishes itself from the sibling 'create_purchase_intent' or 'prepare_purchase_route', which sound like they could do the same thing, so an agent cannot fully disambiguate from the description alone.

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 an implicit precondition — it creates an intent 'only when delegated authority covers the exact fee' — but no explicit when-to-use guidance, no when-not-to-use, and no mention of the sibling tools it must be chosen over. Usage is inferable but not stated.

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