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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered structurally. The description adds real value beyond that by describing what the response conceptually contains (reward titles, descriptions, referral thresholds) and citing the underlying endpoint GET /lists/{uuid}/bonuses. It stops short of mentioning pagination or empty-result behavior, which keeps it from a 5.

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 plus the endpoint path, front-loaded with what the tool returns and immediately followed by the disambiguation. The raw REST path is optional metadata that slightly dilutes the phrasing, but nothing is wasted or buried.

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 single-parameter read-only list tool with a fully documented schema and no output schema, this covers everything an agent needs: what it returns, how it differs from the nearest sibling, and how to get the required id. No meaningful gap remains.

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 coverage is 100% and the uuid property already explains the 12-character MF-prefixed campaign id, so the schema carries the burden. The description only reinforces the 'for a campaign' framing and adds no format or edge-case detail beyond the schema. Baseline 3 is appropriate.

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 (list the rewards configured for a campaign) and names the exact fields returned (title, description, referrals needed). It also explicitly distinguishes itself from referralhero_list_unlocked_rewards, so the agent can separate reward configuration from earned rewards without opening schemas.

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 routing sentence "This is the reward setup, not who earned what: see referralhero_list_unlocked_rewards for that" gives an explicit when-to-use and names the alternative tool by name. Only a campaign uuid is required, and the schema note points back to referralhero_list_campaigns for obtaining it.

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