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

With destructiveHint=true already declared, the description earns credit for disclosing patch semantics ('Only the fields you pass change'), which tells the agent unlisted fields are preserved rather than cleared — a real risk with PUT-style endpoints. It also pins the underlying operation (PUT /v1/campaigns/:id). It does not cover permissions, plan gating, or reversibility.

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 with the mutable-field list front-loaded and the key patch caveat second. The trailing 'Rewardful: PUT /v1/campaigns/:id.' is largely redundant with the already-namespaced tool name and adds little for an agent choosing a 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 10-parameter mutation tool, the schema carries parameter detail, destructiveHint carries the risk profile, and the description adds the one thing structured data omits — that this is a partial update. Missing only error/permission behavior, which is minor given the rich schema and no output schema.

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% and the schema already documents each field's meaning, format and conditional requirements (commission_percent required when reward_type=percent, etc.). The description's field list mirrors the schema without adding syntax, units, or conditional logic, so the baseline 3 applies.

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 ('a campaign'), then enumerates the exact mutable surface: name, URL, visibility, reward rule, payout minimum, coupon. An agent can immediately tell this is the partial-update counterpart to rewardful_create_campaign and rewardful_get_campaign without opening a 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?

The description never says when to reach for this tool versus rewardful_create_campaign, rewardful_get_campaign or rewardful_update_affiliate, and lists no preconditions (e.g. campaign must exist, plan gating). 'Only the fields you pass change' hints at patch semantics but is a behavioral trait, not usage routing.

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