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

Annotations already declare readOnlyHint=false, destructiveHint=true, idempotentHint=true and openWorldHint=true. The description earns credit beyond that by explaining the mechanism that makes it destructive ('import contacts as the recipients'), which implies existing recipient data is replaced, and by clarifying the no-send semantics. It stops short of stating outright that prior recipients are overwritten or what happens when the campaign is not in draft state.

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 short sentences, front-loaded with the 'WRITE:' mutability marker, then the action, then the negative boundary, then the endpoint. 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 two-parameter mutation with full annotations and full schema coverage, this is nearly sufficient: mutability, destructive effect, idempotency and the endpoint are all conveyed. The remaining gap is the precondition (campaign must be a draft) and whether existing recipients are replaced or appended.

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%, with both parameters documented and list_id pointing at sarbacane_list_lists, so the baseline is 3. The description names the two roles (contact list, campaign) but adds no syntax, sourcing, or constraint detail beyond the schema.

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 ('import a contact list's contacts as the recipients of a campaign') plus the underlying endpoint, and explicitly separates itself from the send operation and from content-setting siblings. An agent can tell exactly what this does without opening the 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?

The line 'It does not send the campaign' usefully bounds the operation and prevents an agent from treating it as a dispatch step. However, no alternatives are named (e.g., use sarbacane_set_campaign_content for content, sarbacane_create_email_campaign for creation), and the requirement that the campaign be a draft appears only in the title, not the description.

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