list-categoriesList all available store categories with store counts.
Use to discover what kinds of stores are available before narrowing down. Returns categories sorted by number of stores (most stores first).
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The readOnlyHint annotation already signals safety, and the description adds meaningful behavior beyond it: results are 'sorted by number of stores (most stores first)' and include store counts. This gives agents useful expectations about output ordering and content.
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 appropriately brief and front-loaded: the core function is in the first sentence, usage context follows, and a useful behavioral detail closes it. Every sentence earns its place with no redundancy.
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, parameterless listing tool, the description is fully sufficient. It states the resource, output content, ordering, and when to use it. No output schema exists, but the description covers the essential return semantics without needing more.
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?
The tool has zero parameters and the schema is fully covered by an empty properties object, so parameter semantics are not a concern. The baseline for a no-parameter tool is 4, and the description correctly focuses on output rather than inputs.
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 ('List'), a precise resource ('all available store categories'), and adds a distinguishing detail ('with store counts'). This clearly separates it from siblings like list-stores and search-catalog without needing to inspect schemas.
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?
It gives explicit usage context: 'Use to discover what kinds of stores are available before narrowing down.' It does not explicitly name alternatives or when not to use it, but the guidance is clear enough for an agent to select this tool in the intended workflow.
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: domain status, store capabilities, product variants, categories, store listings, aggregate search, single-store search, and policies. The only similar pair, search-all and search-catalog, is clearly differentiated by scope in their descriptions.
All tool names follow the same lowercase hyphenated verb_noun pattern, such as check-domain, list-stores, and search-catalog. Verbs are consistently placed first and accurately describe each action.
Eight tools is well within the ideal range, and each tool serves a distinct step in the UCP discovery and shopping workflow. There are no redundant or extraneous tools.
The set covers UCP checking, store and category discovery, single-store and multi-store product search, product details, and policy lookup. Direct cart or checkout operations are absent, but discover-store can reveal such capabilities, making the core discovery workflow reasonably complete.