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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds meaningful context beyond that: pricing tiers, free extraction limits, payment mechanisms, and the idempotency-key requirement for cited text. Some of that detail is dense and arguably more about the evidence endpoint than this offer tool, but it still adds behavioral value.

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 is front-loaded, but the pricing sentence is a dense run-on that mixes card packs, per-page pricing, and Stripe MPP calls. 'Example arguments: {}' adds little for a zero-parameter tool, so the paragraph could be tightened.

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 enough by explaining that the tool returns the offer and request schema without purchasing, and by summarizing the pricing tiers. It does not describe the shape of the returned offer/schema in detail, but for a simple informational tool it covers the essential context.

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?

The tool takes zero parameters and schema coverage is 100%, so the baseline is 4. The description includes 'Example arguments: {}', which is redundant but confirms the no-argument nature of the call.

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 clearly states a specific verb and resource: it returns the offer and request schema without buying. It implicitly distinguishes itself from the evidence-fetching sibling by emphasizing 'without buying,' but it does not name or explicitly contrast with proof_fetch_evidence or proof_fetch_preflight.

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?

The phrase 'without buying' implies this is the informational/pre-purchase tool, which gives some usage context. However, there are no explicit instructions about when to choose this over proof_fetch_evidence or proof_fetch_preflight, and no stated exclusions.

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