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

Annotations already flag readOnlyHint=false, destructiveHint=true, idempotentHint=false, so the agent knows this is a mutating, non-idempotent write. The description usefully adds partial-update semantics ('Only the fields you pass change'), which the annotations do not convey, but says nothing about permissions, reversibility, or </query> validation failures.

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?

Two tightly written sentences with no filler. The field enumeration comes first and the partial-update rule is placed last as the key behavioral caveat.

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 destructive, non-idempotent mutation with 8 params, 25% schema coverage and no output schema, the description covers the field surface but stops short. It never tells the agent what a successful update returns or that the call can overwrite state irreversibly, which matters given destructiveHint=true.

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 only 25%, so the description must carry the load, and it does: it names all the optional fields in plain language (title, description, message, schedule→scheduled_at, audience, business-hours rule→trigger_only_during_business_hours, enabled) and explains that unpassed fields are untouched. It omits the audience 'one-off campaigns only' constraint that lives in 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 (change) and resource (campaign) and enumerates the mutable fields, so the agent knows exactly what surface it edits. It does not explicitly distinguish itself from nearby siblings like update_whatsapp_campaign or update_automation_rule, but 'campaign' plus the field list is unambiguous enough to route correctly.

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?

There is no when-to-use guidance, no prerequisites (e.g. that campaign_id must come from list_campaigns), and no mention of alternatives such as create_campaign/delete_campaign/get_campaign. 'Only the fields you pass change' is a behavioral note, not usage guidance.

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