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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description repeats 'Read-only' for reinforcement. The description adds details about the returned attributes but does not disclose additional behavioral traits like pagination, ordering, or auth needs. With annotations covering the main safety profile, this is adequate but not exceptional.

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?

A single sentence efficiently front-loads the action and lists all relevant details (plan names, price in EUR, credit allowance, RPM cap, active projects) without any redundant or vague wording.

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 zero parameters and no output schema, the description fully carries the burden of explaining the tool's return content. It enumerates the included fields and plan names, providing sufficient context for an agent to understand what the tool returns and that it is a read-only 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 tool has zero parameters, so the input schema is empty. The description appropriately does not attempt to explain parameters, and the baseline for no-parameter tools is 4.

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 identifies the action ('List') and the resource ('subscription plans'), naming the specific plans (Free, Pro, Scale) and the attributes returned. It is distinct from sibling tools like get_subscription (current plan) and list_addons (add-ons), which serve different purposes.

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 plan details such as pricing and limits) but does not explicitly mention alternatives or exclusion criteria. For a simple listing tool, this is adequate though not explicit.

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