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

The description adds behavioral context beyond the readOnlyHint and destructiveHint annotations: it confirms no coins are debited and no order is placed. It also discloses the need for sessionId in some cases and the Dixy-specific limitation, all consistent with the annotations. No contradiction.

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 verbose and includes tangential instructions like 'Never ask the owner to edit connector settings or reconnect' and 'Never web-search,' which are not tool-specific and add noise. While the purpose is front-loaded, the extra directives hurt conciseness.

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 mentions the return fields (amount, storeName, itemSummary, needsConfirmation, reviewOnly) and the workflow sequence, which helps. However, it lacks explanations for key parameters like items and store_id, and does not address error handling or edge cases. Given no output schema, this is a moderate gap.

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 coverage is only 29% (2 of 7 parameters have descriptions). The description only adds context for sessionId (pass it and retry if needed) but does not explain items, store_id, lucky, category, or choice_set_id. Given the low coverage, the description should compensate but does not.

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 the tool previews an AgentPay purchase before create_purchase, naming the specific resource and action. It distinguishes itself from create_purchase by stating it does not debit coins or place an order, which prevents confusion with that sibling tool.

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?

Explicitly states when to call it: 'after search_products/get_product and present_choices/clarification, before asking the owner to approve checkout.' It also provides exclusions such as 'Never begin_agent_link again' and 'Never web-search,' giving clear when-not-to-use guidance.

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