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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds valuable operational context: a Word Orb key is required and calls count toward account quota, plus the availability limitation. These are meaningful behavioral traits not present in the annotations.

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?

Three short sentences with zero redundancy. The core action is front-loaded, followed by a necessary availability caveat and an auth/quota note—each sentence earns its place.

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 safety annotations, the description covers purpose, auth, quota, and availability. It doesn't enumerate the exact metadata fields returned, but this is a minor gap given the tool's simplicity and the absence of an 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?

The schema only describes the parameter as 'Word to get images for', while the description refines it to 'an English headword', adding language and form specificity. It also clarifies that the tool returns metadata, not the images themselves.

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?

States a specific verb ('Retrieve available image metadata') and a specific resource ('for an English headword'). This clearly distinguishes it from sibling lookup/search tools that focus on definitions, related words, or translations.

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 implies the tool is for fetching image metadata for a word)Skip, and notes that images are not available for every word, which is a soft caveat. However, it does not explicitly name alternatives or provide when-not-to-use guidance relative to the many sibling tools.

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