purchase_tile

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

No annotations are present, so the description carries the full burden. It does disclose the currency consumed (gold) and clarifies alias handling, but it omits failure conditions (insufficient gold, tile already owned, whether the tile must be adjacent to or within city borders) and turn/timing constraints for a mutation.

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 purpose line is front-loaded and the usage note is well placed, but the Chinese parenthetical about `unit_action` tooling and parameter-name consistency is leaked internal authoring rationale that doesn't help an agent using the 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?

An output schema exists, so return values needn't be explained, and the gold-cost aspect is mentioned. However, for a five-parameter mutation with zero annotations and zero schema descriptions, the description leaves out what constitutes a legal target tile and what the defaulted coordinate properties mean when omitted.

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 0%, so the description must compensate, and it largely does: all five parameters are addressed, and critically it explains that `target_x`/`target_y` are accepted aliases for `x`/`y`, which the schema presents as four separate defaulted properties with no linkage. The odd `-9999` defaults remain unexplained.

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?

States a specific verb and resource combination ("Buy a tile for a city with gold"), which is unambiguous and clearly distinct from the sibling `purchase_item`. It doesn't explicitly name `purchase_item` as the contrasting alternative, so it falls short of full sibling differentiation.

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?

"Use get_purchasable_tiles first to see costs and options" gives an explicit prerequisite step that tells the agent how to sequence this call. It stops short of stating when NOT to use this tool or how it differs in use-case from `purchase_item`.

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