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

The readOnlyHint annotation already establishes this is a safe read, so the bar is lower. The description still adds value by noting results are cumulative 'to date' and that the target must be a sent campaign, but it says nothing about rate limits, permission requirements, or behavior for unsent/invalid campaign IDs.

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 the core purpose and the enumerated metrics, followed by the REST endpoint reference. It is efficient with no filler, though the raw endpoint string is metadata of marginal value to an agent choosing a tool.

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 compensates well by listing the exact returned metrics (opens, clicks, bounces, complaints, forwards, unsubscribes). An agent knows what it will get; the only gap is guidance on scoping or alternatives.

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%; the single campaign_id parameter is fully documented in the schema, including that it is a GUID from moosend_list_campaigns. The description adds no further parameter detail, so the baseline of 3 is appropriate.

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 (Get) and resource (a sent campaign's results to date) and enumerates the exact metrics returned, which implicitly separates it from sibling activity/link-activity tools. It stops short of naming those siblings explicitly, so differentiation still requires the agent to compare names.

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 phrase 'a sent campaign's results' implies the tool only applies to already-sent campaigns, which is a mild usage constraint. However, there is no explicit statement of when to prefer this over moosend_get_campaign_activity or moosend_get_campaign_link_activity, so routing is left to inference.

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