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

Annotations already cover safety (readOnly, idempotent, non-destructive), so the description only needs to add contextual behavior. It does add useful domain detail beyond the annotations: results include whether watches fire under Plus and today's alerts relative to the daily cap, both of which help interpret the output.

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 with no redundant sentences. The parenthetical structure is slightly dense ('the site’s included', 'whether they fire (Plus)'), but overall it communicates efficiently.

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 read-only list tool with an output schema and zero parameters, the description covers the essential scope and the notable behavioral facts (account ownership, Plus firing status, daily cap). It is complete enough to call safely, though richer return-format notes or pagination hints would be a bonus.

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 tool takes no parameters (0 params, 100% schema coverage), so there is no parameter semantics to explain. The baseline for a zero-parameter tool is 4, and the description does not misrepresent any inputs.

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 states a specific verb and resource: 'List your watches', and parenthetically clarifies that watches are the account's alert rules. It is clearly distinguishable from create_watch/delete_watch by verb, but it never names those siblings explicitly, so it does not reach the top score for sibling differentiation.

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?

Use is implied by 'List your watches' and the account-scoping note, but there is no explicit when-to-use guidance, no exclusions, and no named alternative such as create_watch or delete_watch. An agent can infer the purpose but gets no routing instructions.

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