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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description contributes beyond that by specifying the return shape (every trait value with count and percentage), which is the key behavioral fact an agent needs for rarity work.

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 front-loaded sentence with no filler, sized correctly for a one-parameter read tool. The trailing phrase "for rarity questions" is the only part that leans on implication rather than statement.

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 simple, single-parameter read-only tool with no output schema, the description covers what it returns (trait values with counts and percentages) and roughly why. Only edge behaviors such as unknown collection names or large collections remain unaddressed.

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% with a single documented parameter (collection: name, slug or project ID), so the schema already carries the parameter semantics. The description adds nothing about accepted identifier formats or behavior for unknown collections.

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 names a specific resource (trait values within a BrainDrops collection) and the payload returned (count and percentage per value), which separates it from aggregate tools like get_stats and metadata tools like get_collection. It does not explicitly name a sibling, 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?

"For rarity questions" gives an implied usage context, which is better than nothing. However, there is no explicit guidance on when to prefer this over get_stats or get_collection, and no statement of exclusions or prerequisites.

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