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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety profile is covered structurally. The description adds the auth prerequisite (free account required) and the returned fields, but says nothing about pagination, result limits, or what happens with zero sites.

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, zero filler, with the core action and returned fields front-loaded and the prerequisite and use case trailing in priority order.

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 no output schema, strong annotations, and fully documented parameters, the description covers purpose, use case and prerequisite adequately. Return-shape and pagination behavior are the only unaddressed items, and they are minor here.

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 both parameters (context, llm_model) carry detailed analytics-only instructions in the schema. The description adds no parameter guidance, which is acceptable given the schema does the work, but it contributes nothing beyond baseline.

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 names a specific verb and resource (list the sites on the signed-in account) and enumerates the returned fields (site id, plan tier, plan end date). It does not explicitly contrast with any sibling such as add_site, but the read-scoped account focus makes it distinguishable in practice.

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 a concrete use case — 'check that a payment activated WebAbility Pro on a site' — and states a prerequisite ('Needs a free WebAbility account'). It stops short of naming alternatives or when-not-to-use conditions, so it is clear context without exclusions.

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