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

Annotations already declare this as a safe read-only operation, so the safety burden is covered. The description adds useful behavioral context by stating the sort order and clarifying that open/click numbers come from the sent-email ledger rather than a per-campaign counter, but it omits pagination or result-volume behavior.

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 tight sentences with no wasted words. The scope and ordering are front-loaded, and the metric-provenance caveat follows immediately.

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 low-complexity, read-only listing tool with one optional parameter and no output schema, the description is nearly complete: it covers scope, ordering, status inclusion, and data provenance. It could be slightly stronger by mentioning result limits or pagination, but nothing essential is missing.

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 single optional 'project' parameter is already fully explained in the schema. The description's phrase 'in this project' slightly reinforces scope but does not add syntax or fallback behavior beyond what the schema already documents.

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 clearly that it lists campaigns with their status, scoped to a project and ordered newest first. It is easy to separate from other list_* siblings by resource, but it does not explicitly differentiate itself from them (e.g., list_sequences, list_templates).

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 description implies usage by naming the resource and scope, but it gives no explicit when-to-use guidance, no exclusions, and does not point to alternatives such as read_analytics or list_email_deliveries for related data.

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