billing_list_tiers

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

With no annotations, the description carries the full burden of behavioral disclosure. It does reveal the return fields (name, price, monthly credits, billing interval options), which is useful. However, it does not explicitly state that the operation is read-only, whether authentication is required, or that there are no side effects. For a simple parameter-less listing, this is adequate but leaves some implicit assumptions.

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 two sentences long, with the primary action and key details front-loaded in the first sentence. The second sentence adds a useful pointer to the related billing_subscribe tool without redundancy. Every sentence earns its place and there is no unnecessary filler.

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?

Given the tool's low complexity (zero parameters, no output schema), the description is reasonably complete. It covers what the tool returns and its role in the billing workflow via the billing_subscribe reference. Minor omissions around error conditions and authentication are present, but they are not critical for this straightforward list operation.

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 input schema is empty, so there are zero parameters to document. Per the baseline rule for 0-param tools, the description adds value by detailing the output fields, which complements the schema information and gives the user a clear idea of what to expect.

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 states the tool's purpose: to list available PostKing subscription tiers. It specifies a concrete verb ('List') and resource ('available PostKing subscription tiers'), and even enumerates the returned data (name, USD price, monthly credits, billing interval options). This distinguishes it from siblings like billing_subscribe, which creates a subscription, and billing_list_packs, which lists packs.

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 explicitly points to billing_subscribe as the next step for creating a subscription Checkout session, providing an alternative tool for a related action. However, it does not explicitly contrast this tool with billing_list_packs or state when not to use this tool, so it gives only partially clear usage guidance.

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