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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds useful context beyond those annotations: the endpoints are 'signed', scoped to the 'calling account', and the response includes subscribed event kinds. Pagination and rate limits are not mentioned, but those are minor for this simple list operation.

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 focused sentence that front-loads the action and resource, then adds the two most useful qualifiers: account scope and returned event kinds. No filler or redundant phrasing.

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-parameter, annotated as read-only list tool with no output schema, the description is complete enough: it states what the list contains, who it belongs to, and a key output attribute. Nothing an agent needs to call it correctly is missing.

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 zero parameters, so the baseline is 4 and there is nothing for the description to explain. No parameter-level detail is needed.

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 names a specific verb ('List'), a specific resource ('webhook endpoints'), and a clear scope ('registered on the calling account'). It also adds the result content ('event kinds each one subscribes to'), which distinguishes it from the sibling create/delete/rotate webhook tools.

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 correct use case: retrieving the account's webhook endpoint registry rather than creating, deleting, or rotating secrets. It doesn't explicitly name alternatives or exclusions, but the context is clear and no prerequisites are needed for a zero-parameter read-only list.

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