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

Annotations only declare readOnlyHint=true, so the description adds real value: it discloses that results are paged and enumerates the returned fields (name, email, custom fields, tags, preferences, dates). It does not state pagination limits or how to know when to stop paging, keeping it below 5.

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?

Front-loads the core operation and deliverable fields, then adds paging and the API endpoint. Efficient, though the raw endpoint string is marginal information for an agent.

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 no output schema, the description helpfully names the fields returned and flags paging, which is what an agent needs. It leaves pagination termination behavior unstated, but otherwise the definition is complete for a read/list tool.

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% (page, page_size, status enum, mailing_list_id with GUID hint), so the schema already documents every parameter. The description adds the status vocabulary and notes paging, but nothing the schema does not already convey — baseline 3.

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?

States a specific verb (List), resource (subscribers), scope (one mailing list), and the status dimension (Subscribed/Unsubscribed/Bounced/Removed). An agent can distinguish it from sibling reads like moosend_get_subscriber (single) and moosend_list_segment_subscribers (segment scope) without opening the schema.

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?

Usage is implied by the phrasing (filter one list's subscribers by status), but the description never states when to prefer this over siblings such as moosend_list_segment_subscribers or moosend_get_subscriber_by_email, nor any prerequisites. Adequate but with clear gaps.

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