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

With annotations only marking it non-read-only, non-destructive, non-idempotent, and closed-world, the description adds crucial flow details: Stripe card setup via setup_url, monthly budget and per-order cap enforcement, immediate authorization at buy, delayed charge after delivery, and revocation. This is exactly the behavioral context needed for a payment mandate tool.

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?

The description is front-loaded with the buyer use case and packs the payment flow into a few dense sentences without much waste. It could be slightly more explicit about setup_url and return handling, but it is appropriately sized for a complex financial 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?

It explains the mandate lifecycle and charge timing well, but with no output schema the description should be clearer about the return value (presumably setup_url) and what the agent receives after creating the mandate. It also does not cover currency/purpose parameter implications or related status/update tools.

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 already 75%, so the baseline is 3. The description adds meaning for monthly_budget_minor and max_order_minor ('monthly budget', 'cap per order'), but it omits purpose/currency semantics and leaves setup_url unexplained as an input or output artifact.

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 explains that this lets a buyer's principal enable purchases without a payment link, and it names buy as the consuming flow and revoke_mandate as the revocation path. It stops short of a direct 'creates a mandate' verb-resource statement, but an agent can still distinguish it from 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?

It gives a clear triggering scenario: the principal wants purchases without a payment link, saves a card with Stripe once, and sets a budget and per-order cap. It also points to revoke_mandate for undoing the mandate, but it does not state when not to use it or mention related siblings such as mandate_status or set_budget.

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