list_winnersBrands that held a slot when it closed, ranked by what they paid, over the last 24 hours, 7 days or 30 days. Optionally filtered to one category.
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | Defaults to 20. | |
| period | No | Defaults to week. | |
| category | No |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish readOnlyHint=true and destructiveHint=false, so the description only needs to add relevant behavioral context. It does add ranking logic ('ranked by what they paid') and the closed-slot temporal condition, but it does not disclose pagination, ordering direction, or any rate-limit/auth nuance. This is acceptable but not exceptional for a read-only listing tool.
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 dense sentence that front-loads the core result ('Brands that held a slot when it closed'), then adds ranking and the two key filters. There is no filler, repetition, or boilerplate.
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 simple list tool with zero required parameters and a read-only annotation set, the description provides enough to invoke it correctly: what is returned, how it is ranked, which time windows are available, and that category filtering is optional. It does not explicitly state ascending/descending order or pagination behavior, but those gaps are minor for a read-only list query and the input schema already covers defaults.
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?
With schema description coverage at 67%, the description meaningfully compensates for the undocumented category parameter by saying filtering is optional. It also translates the period enum into user-facing time windows ('last 24 hours, 7 days or 30 days'), which clarifies the intended values. The limit parameter is already well-described in the schema, so the description need not repeat it.
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 names the resource ('Brands that held a slot when it closed') and specifies the action/list semantics with a unique qualifier: 'ranked by what they paid.' The 'when it closed' framing distinguishes it from current-board tools like get_board without needing to name 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 rather than stated: an agent can infer this tool is for retrieving historical slot winners, but the description never articulates when to choose it over get_stats, get_slot_price, or get_board. It focuses on operational filters (period, category) rather than selection guidance or exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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Each tool targets a distinct resource or action, but get_slot_price and get_board overlap in that the board already shows how much slots are held for and which are free. The remaining tools are clearly separated by board, brand, site, and winners.
All tool names use a consistent verb_noun snake_case pattern: get_board, get_stats, get_slot_price, get_brand_stats, list_winners, and claim_free_slot. The mix of get and list is predictable and readable.
Six tools is well-scoped for this domain, covering board state, pricing, statistics, winners, and the one free-slot mutation. Each tool earns its place without bloat or thinness.
The read and analytics side is well covered, and free-slot claiming is possible, but the core bidding/outbid lifecycle is absent: get_slot_price tells an agent what it would take to take an occupied slot, yet there is no place_bid, update_bid, or release tool. This leaves a notable dead end for participating in the main BidSurvivor mechanic.