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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds genuinely useful context beyond that: the full status code mapping (0 draft, 1 queued, 3 sent, 5 awaiting delivery, 6 sending), the pagination ceiling of 1000, and the underlying endpoint shape. It stops short of describing ordering defaults in prose, but the operational picture is clear.

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?

Two tight sentences: the returned payload first, then pagination and endpoint. The status enumeration is verbose but it is high-value decoding information, and nothing is padded or redundant.

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 must carry the return-shape burden and does so well, naming the stat fields and pagination behavior. It does not state totals/paging metadata or default sort order in prose, which leaves a small gap for a list endpoint, but an agent has enough to call and interpret it.

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%, so page, page_size, sort_by and sort_method are already fully documented with defaults and enums. The description only restates the 1000-per-page bound and never mentions sorting, so it adds essentially nothing the schema does not already carry.

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 and resource ('List campaigns') and then enumerates exactly what comes back: status codes, delivery/schedule dates, target lists, and headline stats. This makes it trivially distinguishable from the singular moosend_get_campaign and the many get_* siblings in the toolset.

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 plural 'List' versus the sibling get_campaign/get_campaign_summary implies this is the enumeration path, and the pagination note implies bulk retrieval. However, there is no explicit statement of when to prefer this over get_campaign_summary or get_campaign_activity, so usage is only implied.

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