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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered; the description adds the non-obvious default filter set and sort order, which the agent cannot infer from annotations. It doesn't mention the paging cap (limit max 500) or total counts, but those are largely in the schema.

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-loaded with purpose and returned fields, then defaults, then paging, in three tight sentences with no filler. The inline status-code legend is dense but earns its place for an agent printing results.

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 rightly lists returned fields, default scope, sort order, and how to paginate – enough to call it correctly. It omits filter interactions (e.g., how include_archived combines with mailing_types) but the gaps are minor for a read-only 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%, so the baseline is 3. The status legend and type glosses repeat what the schema enums already say; the only genuine addition is the cross-reference that 'start' should come from next_start in the previous reply.

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?

Opens with a specific verb+resource ('List mailings (campaigns)') and enumerates the returned fields, so the agent knows exactly what comes back. It implies the distinction from emma_get_mailing (single) only through the plural noun, so it doesn't fully differentiate from siblings.

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?

States the default scope precisely ('standard and test mailings in all statuses, newest first') and gives an explicit paging protocol ('use next_start'). It never names an alternative tool or when-not to use this one, keeping it short of a 5.

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