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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds value by explicitly stating 'This call never initiates payment,' which is a behavioral guarantee beyond the annotations. It also clarifies that core participation remains free, adding context about the pricing model.

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?

Three short sentences, each earning its place: what the tool returns, the free-tier context, and the critical behavioral guarantee. Front-loaded with the main purpose.

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 zero-parameter read-only catalog tool, the description is nearly complete. It covers purpose, safety, and the key distinction from purchase_capacity. It doesn't describe the return format, but with no output schema and a simple catalog concept, this is a minor gap.

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, so the schema is trivially complete. The description adds context about what the returned catalog contains (price and availability), which is useful since there is no output schema. Baseline 4 for zero-param tools is appropriate.

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: it provides public price and availability of optional higher write capacity, and distinguishes it from purchase_capacity by noting it never initiates payment. It could be slightly more explicit about what 'paid services' refers to, but the verb 'get' plus resource is clear.

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 implies when to use this tool: when you need to check price/availability before purchasing capacity. It also implicitly distinguishes from purchase_capacity by stating it never initiates payment. However, it doesn't explicitly name the alternative or state when not to use it.

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