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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description goes beyond that by disclosing exactly what data comes back (active status plus sender/receiver rewards) and the underlying HTTP endpoint, which is valuable since there is no output schema. It does not discuss auth, rate limits, or error behavior, keeping it short of 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?

A single compact sentence front-loads the verb and resource, enumerates the return fields inline, and closes with the API mapping. Nothing is wasted and nothing essential is 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?

With no output schema and no parameters, the description carries the burden of telling the agent what comes back, and it enumerates the active flag and both reward types. It stops short of covering edge cases (e.g., behavior when the program is unconfigured) or auth/error conditions, so it is strong but not exhaustive.

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?

The tool has zero parameters and 100% schema description coverage, so the baseline of 4 applies. The description correctly adds no parameter detail because there is nothing to document.

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 states a specific verb ('Fetch') and resource ('the referral program's configuration'), and even enumerates the returned fields (active flag, advocate reward, friend reward). It is clearly distinguishable from the sibling 'get_points_settings' by resource, though it never explicitly names or contrasts against any sibling tool.

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?

No explicit when-to-use guidance or alternatives are given. For a zero-parameter read-only configuration getter the usage is strongly implied (call it when you need the referral program's config), which fits the 'implied usage' bar of 3, but nothing tells the agent when not to use it or which sibling to prefer.

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