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

Annotations already declare it read-only, idempotent, and non-destructive, so the description need not repeat those. It adds useful context by specifying that the response is JSON and includes the current baseline image URL and status, which are not 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?

The description is a single sentence that front-loads the verb and object, states the key output fields, and includes the response format. There is no wasted wording or unnecessary detail.

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 operation, the description is sufficiently complete: it identifies the input, the output format, and the key fields returned. Error behavior is not mentioned, but given the simplicity and strong annotations, this is a minor gap.

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 has 100% coverage and already explains that 'id' is a UUID. The description adds no additional semantic meaning beyond repeating the ID reference, so the baseline score of 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 uses a specific verb and resource ('Fetch one watch by ID') and clarifies scope ('one watch') and key outputs ('baseline image URL and status'). This clearly distinguishes it from sibling tools like watch_list, which would fetch multiple watches.

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 the tool is for retrieving a single watch by its ID, which is the correct context. It does not explicitly name alternatives or when-not-to-use, but the singular 'one watch by ID' provides adequate guidance.

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