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

Annotations already declare destructiveHint=true, lowering the bar. The description adds two useful behavioral facts — that a reward rule is created atomically with the campaign, and the underlying endpoint POST /v1/campaigns — but says nothing about permissions, uniqueness constraints on name/url, idempotency, or rate limits.

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 core action, and no filler. The trailing 'Rewardful: POST /v1/campaigns.' is marginally useful for traceability but adds little for an agent deciding how to call the tool.

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 9-parameter create tool with no output schema, the description covers the action, the coupled reward-rule semantics, the conditional field requirements, and the endpoint. It omits what the call returns and any error/permission conditions, which is a modest gap given annotations carry the safety profile.

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 schema already documents every parameter, including the 'Required when reward_type is percent/amount' conditions. The description's conditional parameter routing largely restates what the schema says, adding little beyond the 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+resource ('Create a new affiliate campaign') and clarifies scope by noting the reward rule is created alongside it. An agent can immediately distinguish this from rewardful_get_campaign, rewardful_list_campaigns, and rewardful_update_campaign.

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 conditional invocation guidance (pass commission_percent for percent, commission_amount_cents/currency for amount), but offers no when-to-use context versus siblings such as update_campaign, and no prerequisites or exclusions. Usage is implied rather than framed.

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