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

There are no annotations, so the description carries the full behavioral burden. It conveys a read-only lookup behavior by saying 'Look up' and specifies the return type as 'text.' It does not cover edge cases like unknown words or multiple definitions, but these are not critical for a simple dictionary lookup tool.

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?

The description is a single, front-loaded sentence that directly states the action, scope, and output. Every word earns its place and there is no unnecessary elaboration or repetition.

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 lookup tool with an output schema, the description is substantially complete. It covers the input type ('English word'), the operation, and the return format ('text'). It does not mention failure behavior, but that is a minor gap given the tool's simplicity.

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 input schema only has a parameter titled 'Word' with zero description coverage. The description compensates by specifying that the word must be an English word, which adds meaningful semantic context beyond the schema. Though format and edge cases are not detailed, the parameter and its expected value are straightforward.

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 uses a specific verb ('Look up') and a clear resource ('the definition of an English word'), and it states the output form ('return it as text'). There are no sibling tools, so no differentiation is needed. This makes the tool's purpose immediately obvious.

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 description clearly implies when to use the tool: whenever an agent needs to retrieve the meaning of an English word. It also implicitly excludes non-English words. Because there are no sibling tools or alternatives, explicit when-not-to-use guidance is not necessary.

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