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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds real behavioral context beyond that: the pagination ceiling of 1000 per page and the underlying endpoint. It does not cover auth needs, rate limits, default page size, or sort defaults, so it is useful but not rich.

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 dense sentences that front-load what is listed and follow with pagination and endpoint details. The status code enumeration is long but genuinely informative; nothing here is filler, though the run-on status list slightly dilutes the front-loading.

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 reasonably compensates by naming the fields a caller can expect (status, dates, target lists, sent/opens/clicks/bounces/unsubscribes/complaints). Combined with the readOnly annotation, an agent has enough to call this correctly; only the absence of use-case routing keeps it from being fully complete.

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 the schema documents page, sort_by, sort_method and page_size with enums and defaults. The description adds essentially nothing on parameters (the '1000 per page' note merely echoes the page_size maximum), so the baseline 3 is correct.

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+resource ('List campaigns') and enumerates the returned fields (status, delivery/schedule dates, target lists, headline stats), which is more than a bare restatement of the title. It is clearly a bulk/paged listing rather than the single-resource sibling moosend_get_campaign, though it never names that distinction explicitly.

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?

There is no guidance on when to reach for this tool versus moosend_get_campaign, moosend_get_campaign_summary, or moosend_list_mailing_lists. The description only describes contents and pagination ('Paged, up to 1000 per page'); the use case is left to inference with no exclusions or alternatives named.

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