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

The description adds real context beyond annotations: paid access terms (0.10 USDC per call, 10 free calls per rolling 30 days), that credentials, signed mandates and single-use grants are still required, that no server credentials are supplied, and that payment confers no spending authority. This is valuable for an openWorldHint=true tool, though the pricing boilerplate overshadows the actual evaluation semantics.

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 core purpose appears only in the second sentence, behind pricing and payment boilerplate that belongs in a footnote. The 'grants no authority' idea is restated twice ('This adapter grants no authority' and 'Payment is an API access fee and grants no spending authority'), padding an otherwise short description.

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?

With no output schema, the description does convey that the return is an allow-or-deny preview plus reasons, which is helpful. However, for a tool with five required nested-object parameters and zero schema descriptions, it omits the input contract details an agent needs to construct a valid evaluation request.

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% and the five required parameters are deeply nested, yet the description only says to 'supply policy, usage and request values' without explaining any field. It gives no guidance on units (minor/cents), the fee_minor versus run_count relationship, mode, or how policy fields like budget_minor and max_action_fee_minor drive the decision, so it fails to compensate for the coverage gap.

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 names a specific action and resource: 'Compare a proposed request with the policy, usage and budget values you supply and return an allow-or-deny preview,' plus the endpoint POST /api/agent-budget-guard. It is clear what the tool does, but it never contrasts itself with plausible siblings such as wever_payment-authority-inspector or wever_ap2-mandate-gateway, so differentiation must be inferred.

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?

'An agent checks the preview before the payment flow; a human sets the budget and approves any exception' gives a concrete when-to-use context and a division of responsibility. It stops short of naming an alternative tool or an explicit when-not-to-use condition.

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