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

Annotations only supply destructiveHint=true, so the description must add context, and it does disclose that creation also creates the associated reward rule and that it maps to POST /v1/campaigns. It omits side effects beyond that, such as permission requirements, idempotency/duplicate handling, or whether the reward rule can be revised later.

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: purpose first, conditional parameter rule second, API mapping last. Every sentence carries information and nothing is padded.

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 creation tool with full schema coverage and no output schema, the description covers the core risks: that it creates two entities (campaign + reward rule) and which parameters pair with which reward_type. It lacks any note on the returned object or on the meaning of optional fields like private/minimum_payout, but the schema carries those.

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's conditional guidance duplicates what the schema already states ('Required when reward_type is percent/amount'), adding no syntax, default, or format detail beyond 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?

The description gives a specific verb and resource ('Create a new affiliate campaign with its reward rule'), which cleanly separates it from the get_/list_/update_campaign siblings. It does not explicitly name a sibling it should be chosen over (e.g., update_campaign), so it stops short of a 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?

It provides conditional usage for the reward parameters ('For reward_type percent pass commission_percent...'), which is genuine when-to-use guidance at the parameter level. However, there is no guidance on when to choose this tool versus rewardful_update_campaign or how it relates to the affiliate-creation siblings, 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.