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

Annotations already declare destructiveHint=true, idempotentHint=false and openWorldHint=true, so the safety profile is covered. The description adds value beyond that by stating the real-world consequence (which campaigns can spend how much per day) and pointing at the dry-run path, though it says nothing about permissions or propagation timing.

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 short sentences, the effect front-loaded before the safety advice, with zero filler. Every clause 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 destructive five-parameter mutation with full schema coverage, no output schema, and annotations covering the safety hints, the description supplies the impact and validation guidance an agent needs. It leaves open only secondary details such as permission requirements and whether extraFields carries hidden risk.

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%, including detailed docs for amount, customerId, extraFields and validateOnly, so the schema already carries the parameter burden. The description only echoes the 'daily amount' and dry-run concepts, adding no syntax or format detail beyond the schema's baseline.

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: changing the daily amount on an existing campaign budget. This implicitly separates it from create_campaign_budget and from update_campaign, but it never names a sibling or the boundary explicitly, so it falls just short of 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?

"Dry-run it first if you are unsure" gives a concrete precondition tied to validateOnly, which is real guidance. However, there is no routing advice against alternatives such as update_campaign or create_campaign_budget, so usage is only partially covered.

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