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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds useful behavioral context by explaining that paid plans add weekly re-scans with email briefs and explicitly reinforces 'Read-only lookup.' No contradictions with annotations.

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 compact and front-loaded: the core purpose appears in the first sentence, followed by return behavior, plan context, safety indication, and parameter documentation. Every sentence earns its place, and the Args section is cleanly formatted.

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 single-parameter read-only lookup, the description covers the purpose, the input format, the output concept ('enrollment status'), and the meaning of the plan. Annotations handle safety and idempotency, so nothing essential is missing for correct selection and 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?

The input schema provides no description for 'domain,' so schema coverage is 0%. The description compensates fully by documenting the 'domain' argument with a concrete example ('e.g. example.com'), giving the agent exactly what it needs to supply the parameter correctly.

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: 'Check whether a domain is enrolled on a paid weekly monitoring plan.' It clearly identifies the tool's purpose as an enrollment/status lookup, which distinguishes it from siblings like pw_health, pw_snapshot, and pw_stats even without naming them.

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 makes the usage context explicit: use this when you need to determine whether a domain has paid weekly monitoring, and it notes the lookup is read-only. It does not explicitly contrast with sibling tools or state when not to use it, but the intended use case is clear enough for an agent to select it.

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