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

Annotations already declare readOnlyHint=false and destructiveHint=true, and the description goes beyond them by explaining what that destruction means in practice: real emails resume going out on the existing schedule. It does not address the non-idempotent hint (i.e., that repeated calls or double-resume may be problematic), so it is good but not complete.

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?

One sentence, front-loaded with the action, zero filler. It is a little thin for a mutation tool, but nothing is wasted and the key consequence is stated 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 simple one-parameter state-change tool with annotations covering the safety profile and a fully documented schema, the main missing piece an agent needs — the real-world effect of resuming — is present. Remaining gaps (idempotency, auth requirements) are minor.

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?

Single parameter with 100% schema description coverage ('Campaign id (UUID)'), so the schema fully documents it. The description adds no additional meaning about the id, which is expected — 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?

Specific verb 'resume' plus resource 'campaign', and 'a paused campaign' implicitly separates it from start_campaign (which begins a new send) and pause_campaign. It stops short of naming those siblings explicitly, so an agent must infer the routing.

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 paused campaign' implies the precondition (the campaign must currently be paused), which is useful context. However, there is no explicit statement of when to prefer this over start_campaign, nor any note about required permissions or failure modes if the campaign is not paused.

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