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

readOnlyHint=true already tells the agent this is a safe read with no side effects, so the description's burden is lighter. The metric list adds useful detail about what data is exposed, but nothing is said about error behavior for unsent campaigns, rate limits, or authentication requirements.

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 sentences, front-loaded with the metric list before the endpoint reference; every clause carries information. The raw API path is marginally redundant for an agent but is compact and harmless.

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 usefully enumerates the returned fields (sent, opens, clicks, bounces, complaints, forwards, unsubscribes), which is exactly what the agent needs to interpret results. It is only slightly incomplete regarding failure behavior for a non-sent campaign.

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 coverage is 100% and the single campaign_id parameter is already documented as a GUID sourced from moosend_list_campaigns. The description adds no syntax, format, or sourcing detail beyond that, 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?

The description states a specific verb (get) and resource (a sent campaign's results to date) and enumerates the exact metrics returned, which lets an agent separate it from generic siblings like moosend_get_campaign. It does not name or contrast those siblings explicitly, so it falls short of a 5.

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 only an implicit precondition that the campaign must already be sent; no when-to-use, when-not-to-use, or alternative is offered. Given the dense cluster of similar siblings (moosend_get_campaign, moosend_get_campaign_activity, moosend_get_campaign_link_activity), the absence of routing guidance is a real gap.

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