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

Annotations already declare readOnlyHint=true, so safety is covered; the description adds real value on top by scoping exactly which campaign data is and is not returned and by citing the underlying endpoint. It stops short of noting auth requirements or response size/format, so it is not perfect, but it is well beyond restating annotations.

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 compact sentences, front-loaded with the primary purpose, then the exclusion/alternative, then the API mapping. Every clause carries information; no filler.

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?

There is no output schema, so the description carries the burden of describing return content — which it does by listing the field groups the agent will receive. Combined with the exclusion pointing to the summary tool, an agent has everything needed to call it correctly.

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% and there is only one parameter, whose schema description already explains the GUID format and its source (moosend_list_campaigns). The description adds no additional parameter-level detail, 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 ('Get one campaign's details') and then enumerates the actual fields returned (subject, sender/reply-to, HTML/plain content, target lists/segments, schedule, status, A/B data). It also names the sibling it is not, so an agent can distinguish it from moosend_get_campaign_summary without opening either schema.

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?

Explicitly excludes statistics and routes the agent to the correct alternative ('No statistics (use moosend_get_campaign_summary)'). The schema's parameter description further supplies the prerequisite chain, telling the agent to obtain the ID from moosend_list_campaigns.

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