List newsletter subscribers

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

The description adds behavioral context beyond the annotations: it states that no email is sent, no subscriber is added/removed, and that it returns personal data requiring confidentiality. The annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the description reinforces and adds the privacy warning, which is valuable. It doesn't contradict 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 concise and well-structured, with a clear first sentence stating the purpose, followed by usage guidance, safety/privacy notes, and pagination details. Every sentence adds value, and it's appropriately sized for the tool's complexity.

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?

Given the tool's simplicity (2 optional params, no output schema, no nested objects), the description covers all necessary aspects: purpose, usage, safety, privacy, and pagination. It's complete for an agent to use correctly without further clarification.

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 already provides full descriptions for both parameters (limit and offset) with defaults and ranges. The description mentions pagination with limit and offset and the default of 20, but doesn't add much beyond the schema. Since schema coverage is 100%, a 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 clearly states the tool lists newsletter subscribers for the authenticated account, with pagination. It distinguishes itself from the sibling tool list_newsletter_issues by explicitly noting the difference between subscribers and sent issues.

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 provides explicit guidance on when to use this tool (to size audience or export list) and when not to (for sent issues, use list_newsletter_issues). It also mentions the requirement of an API key and the read-only nature, which helps the agent decide when to invoke it.

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