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

The annotation only says readOnlyHint=false, so the description must carry behavioral weight. It does add one genuinely useful fact — the commission is deducted from the proceeds at sale time — plus the fact that count applies to stacks, but it omits whether the item leaves the backpack immediately, whether a listing can be cancelled or retrieved, and any permission requirements.

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?

A single dense sentence with the core action front-loaded and clarifying detail in parentheses. Nothing is wasted, though the nested parenthetical makes it slightly harder to scan than a two-clause version would be.

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 three-parameter mutation tool with no output schema and minimal annotations, the fee disclosure and price format cover the essentials, but an agent still cannot tell what state change occurs to the inventory item or whether the listing is reversible.

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%, so the description must supply parameter meaning and largely does: price is per unit and is a string containing a dot as decimal separator, and count applies only when listing a stack. Only item_id is unexplained, which is close to self-evident.

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: listing an item from the backpack on the auction at a fixed price. That verb distinguishes it from game_auction_buy, game_auction_take and the generic game_auction, although it never names those siblings explicitly.

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?

Usage is implied by the phrase 'from the backpack' and the fixed-price framing, but there is no explicit when-to-use or when-not-to-use guidance and no mention of how this relates to the other auction tools. The commission note hints at trade-offs but is not framed as selection guidance.

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