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

Annotations already mark this as read-only and idempotent, but the description adds substantial behavioral detail: scope-dependent return fields, anonymous/missing-scope behavior, pricing display differences, and the role of Preview in confirming final charges. This is unusually transparent 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 opening sentence is front-loaded and every subsequent sentence carries useful information about access, return fields, or pricing. It is somewhat dense and run-on, but not padded.

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?

With no output schema, the description must carry return-value context, and it does: it names the relevant fields and explains the publicCatalog pricing nuance. For a one-parameter read-only listing tool with annotations, this is complete enough for correct invocation.

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 100%, and the single includeUnavailable parameter is already fully documented in the schema. The description does not add meaning beyond that schema detail, so the baseline of 3 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 opens with a specific verb and resource: "List models, parameters and prices." It also distinguishes the tool from siblings by explicitly pointing to account for balance and spending_policy for limits.

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 clear usage context by explaining authenticated vs anonymous behavior and naming account and spending_policy as alternatives for related but different needs. It does not explicitly state when not to use this tool beyond those alternative routes.

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