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

Annotations already cover the safety profile (readOnly=false, idempotent=true, destructive=false), so the bar is lower; the description still adds meaningful context by naming the two validation checks that gate success and clarifying that this does not activate. It does not say what happens if validation fails (error shape) or what the response contains, which keeps it short of a 5.

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 tight sentences with zero waste; the state change is front-loaded, validations second, and the sibling-exclusion last. Every sentence earns its place.

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 one-parameter mutation with no output schema, the description covers the state change, the validation gates, and the non-activation caveat. The only gap is failure/response behavior, which is minor given the tool's simplicity.

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 coverage is 100% and the single campaign_id parameter is already documented in the schema with a pointer to list_campaigns. The description adds no format, source, or constraint detail beyond what the schema provides, so 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 ('Mark a campaign setup complete') plus the resulting state change (is_draft: false), and explicitly distinguishes itself from the sibling activate_campaign. An agent can tell exactly what state transition this performs.

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 states the boundary condition: 'Does not activate the campaign; use activate_campaign separately.' It also implies the precondition context (campaign has email step and sender profile) that must hold before use, giving both when-to-use and the named alternative.

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