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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds two genuinely new operational facts the annotations do not: the call is free and an API key is required. It stops short of noting pagination or result limits, which keeps it at 4.

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?

Two short sentences, zero waste, and the resource scope is front-loaded ahead of the cost/auth note. Nothing is repeated from the title or annotations.

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 zero-param read tool with rich annotations and an output schema, the description covers what is missing from structured fields: cost and authentication. Only the absence of any result-volume or pagination hint keeps it just short of complete.

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, so per the baseline the schema cannot be improved upon and 4 applies by default. The description correctly introduces no parameter concepts that do not exist.

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 the resource and scope precisely: every live watch on the account, with 'live' adding a meaningful filter the name alone does not convey. It is clearly distinct from the lookup_* siblings and from watch/unwatch, though it relies on the tool name to supply the verb 'list'.

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?

Usage is only implied: an agent can infer this retrieves watches while watch/unwatch modify them, but the description never says when to call this versus those siblings or any precondition beyond an API key. For a zero-parameter listing tool the implied path is short, so 3 rather than 2.

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