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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description reinforces this with 'Writes nothing' and, more valuably, discloses the two-step preview-then-apply workflow that annotations cannot express. It does not mention behavior on ambiguous or rejected changes, so it stops 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 short sentences, front-loaded with what the tool does and immediately followed by the workflow instruction. Every clause carries information; nothing is 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?

There is no output schema, and the description compensates by stating the return is 'exactly what would change', which tells the agent the response is a diff-style preview. The only gap is error or ambiguity handling for unparseable change descriptions, which is minor for a read-only planning tool.

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 baseline is 3. The description goes further by supplying four concrete examples of the natural-language 'change' input ('only send on weekdays', 'cut it to 10 a day', etc.), which teaches the agent the expected input register in a way the schema string alone does not.

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 (describe/plan), the resource (a campaign change), and the scope (preview only, writes nothing). It explicitly contrasts with the sibling apply_campaign_change, so an agent can route between the two without opening either 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?

Gives an explicit when-to-use workflow: call this first, show the result to the person, then call apply_campaign_change with the same changes to make it real. The alternative and the condition that selects it are both named, leaving nothing to inference.

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