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

Annotations already declare readOnlyHint=true, so safety is covered and the description's bar is lower. The description does add the pagination model ('Cursor-paginated') and the underlying endpoint, which is genuinely useful context, but it says nothing about rate limits, ordering, or the shape of the result envelope.

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?

Three short sentences, front-loaded with what the tool lists and its filter, followed by pagination and endpoint metadata. 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 partly compensates by disclosing cursor pagination, and all three parameters are documented in the schema. It stops short of describing the response payload (subscriber fields, meta cursor location), which an agent stitching pages might want.

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%: limit, cursor, and status are each fully documented in the schema, including enum values and the filter[status] mapping. The description's 'optionally filtered by status' merely restates the schema, so the baseline 3 applies.

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 subscribers') plus an optional filter, so the agent immediately knows this is the account-wide subscriber read. It does not, however, differentiate itself from siblings like mailerlite_get_subscriber (single) or mailerlite_list_group_subscribers (scoped list), which an agent would have to infer.

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?

'Optionally filtered by status' implies the filtering use case, which is the only guidance given. There is no statement of when to prefer this over get_subscriber or list_group_subscribers, and no prerequisites or exclusions.

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