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

The annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely new context beyond them: activation triggers recurring generation with credit caps and, crucially, 'Previously approved automatic delivery can publish to connected channels' — an external side effect the agent would not otherwise anticipate. It does not address permissions or rate limits, so not 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 short sentences, front-loaded with the activation action, and each carries information. 'Only advertising artwork' is slightly clipped in phrasing but costs no space. No padding.

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?

An output schema exists, so return values need not be described, and the annotations carry the safety profile. What remains missing is the prerequisite chain (prepare/resume siblings) and any meaning for the four required parameters, which for a destructive activation tool is a real gap.

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 0% and all four parameters (brandId, automationId, revision, idempotencyKey) are required with no descriptions. The description never explains any of them — notably the concurrency meaning of 'revision' (an exclusiveMinimum integer) or the 8-128 character idempotencyKey — so it fails to compensate for the coverage gap.

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 (activate) and resource (recurring generation via the saved recipe/credit caps), and scopes it with 'Only advertising artwork; the saved automation type must match this tool.' That constraint is what separates it from the ~20 sibling activate_* automation tools. It stops short of naming a specific sibling, so it lands at 4 rather than 5.

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 'the saved automation type must match this tool' gives an implied precondition for use, but there is no explicit guidance on when to activate versus resume_ad_creative_builder_automation or pause_automation, nor any mention that a saved automation must first exist (prepare_ad_creative_builder_automation). Usage is inferable but not stated.

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