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

The annotations already declare readOnlyHint=true and idempotentHint=true, covering the main behavioral profile. The description is consistent with those annotations and adds scope details about what is listed, but it does not disclose extra behavior such as locale handling, pagination, or response shape beyond the output schema.

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, front-loaded sentence that immediately states the action and resource, then lists the key content areas. There is no filler, repetition, or unnecessary detail.

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 read-only list tool with an optional parameter and an output schema, the description covers the essential scope and safety context. It is slightly incomplete because it does not clarify how locale affects output or when to prefer this over closely related sibling tools, but these are minor gaps.

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 only parameter, locale, has no description in the schema (0% coverage) and is not mentioned in the tool description. An agent must infer from the enum and default that it controls language, but the description does not compensate for the missing schema descriptions.

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 uses a specific verb ('List') and resource ('current plans') and enumerates the fields returned (prices, limits, seats, modules, checkout mode). It is clear about the tool's function, but it does not differentiate it from sibling tools like get_offer or compare_offers, which could overlap in purpose.

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?

There is no guidance on when to use this tool versus alternatives. With siblings such as compare_offers and get_offer, an agent gets no explicit direction about which tool fits which scenario, leaving usage entirely to inference.

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