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

Annotations already declare that this is a read-only, idempotent, non-destructive open-world query. The description adds useful behavioral context by saying results are paged, the limit range is 1-100, dates are optional, and the returned fields include email, name, lists, and open time.

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?

The description is compact and front-loaded: one sentence states the core purpose, and a short parenthetical adds paging and date-filtering context. Every sentence carries useful information with 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?

For a read-only, fully documented 5-parameter query tool with no output schema, the description is largely complete: it names the returned fields, notes pagination, and explains date filtering. It omits the page parameter and default limit size, but the schema covers those details.

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 all five parameters are already documented in the input schema. The description mentions paging, the limit range, and optional date_from/date_to, but those details largely repeat the schema and it does not explain the page parameter or add syntax beyond what is already provided.

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 and resource: list contacts who opened a campaign. The word 'opened' distinguishes this from sibling report tools such as get_campaign_clicks and get_campaign_unsubscribes, and the returned fields make the purpose concrete.

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?

Usage is implied by the purpose: use this to list contacts who opened a campaign, optionally filtered by date. However, the description does not explicitly say when to choose this over adjacent siblings like get_campaign_clicks or get_campaign_unsubscribes, and it gives no exclusions.

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