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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description adds genuinely useful behavior beyond that: alias matching and the fallback that an unknown term returns the list of available terms, which tells the agent how to recover from a miss.

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?

It is a single front-loaded sentence that leads with the action and resource. The long parenthetical enumeration is dense but earns its place by delimiting scope.

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 one-parameter lookup with no output schema, the description covers scope, alias behavior and the unknown-term fallback, which is enough for correct invocation. Return-format details are not required since the lookup is a simple definition.

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 single 'term' parameter already documents its purpose with examples ('lafufu', 'printed odds'). The description adds only the vocabulary list, which overlaps with the schema examples, so the 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?

The description names a specific verb (define) and resource (a Labubu/blind-box collecting term) and enumerates the covered vocabulary, so the agent knows exactly what this tool answers. It is clearly distinct from siblings that compute odds or display plans.

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?

It implicitly scopes usage to looking up the meaning of a collecting term and notes alias matching, giving the agent a clear context for invoking it. It does not explicitly contrast itself with get_collecting_guide or the other sibling tools, so no exclusion guidance is provided.

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