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

readOnlyHint=true already establishes this is a safe read operation, lowering the disclosure bar. The description usefully adds behavioral context about the returned data ('whether the grant is still active'), which goes beyond the annotation. However, it says nothing about pagination behavior or result shape despite having no output schema, so it adds only moderate value.

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 compact sentences with zero waste, front-loading the core action and purpose. The endpoint mapping is a useful trailing detail that does not detract from the front-loaded purpose.

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, the description carries the burden of explaining return values, and it partially does so by noting grant recipients and active status. It omits pagination behavior and the overall response structure, leaving gaps for a list tool. Adequate but incomplete given 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%, so page, limit, and benefit_id are already fully documented in the schema. The description adds no extra meaning about parameter syntax, ranges, or defaults beyond what the schema provides. Baseline 3 is appropriate when the schema does the heavy lifting.

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 ('List who has been granted one benefit') and clarifies scope with 'of one benefit,' implicitly distinguishing it from the sibling polar_list_benefits. It clearly conveys this returns grant records rather than the benefits themselves. It stops short of explicitly naming a sibling alternative, so it lands at 4 rather than 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?

There is no explicit when-to-use guidance and no mention of the alternative polar_list_benefits for enumerating benefits. The reader can infer the tool requires a benefit_id, but there is no statement of prerequisites or when this should be preferred over other list endpoints. This is minimal implied usage only.

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