Buy a shop item

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

Annotations already mark this as destructive. The description adds valuable behavioral details: it performs validations (SHOP, index, funds, slot insufficiency) before buying. This goes beyond the annotations, though it doesn't describe the full side effects (e.g., item removal, money deduction).

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 a single, concise sentence in Chinese. It front-loads the primary action and adds a compact validation note. No wasted words.

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 straightforward shop-buy action with three parameters and no output schema, the description covers the core purpose and important preconditions. It lacks details about post-buy state changes, but the destructive annotation and game context make it sufficiently complete for the agent.

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 100%, with each parameter (kind, index, expected_state_token) already documented. The description adds no parameter-specific meaning beyond mentioning 'index' and 'funds' in the validation context, which is not substantial.

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 states a specific verb and resource: '购买商店物品' (buy a shop item). It clearly distinguishes this from siblings like sell_item and discard_cards. The additional validation mention further clarifies the tool's scope.

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 description implies usage when the agent wants to purchase a shop item, but provides no explicit guidance on when not to use it or alternatives. The validation note ('先校验 SHOP、索引、资金及明显的槽位不足') gives context about preconditions but not tool selection.

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