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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds real behavioral context beyond that: it requires an authenticated Proof account and a re-authentication step, which an agent must know before invoking. It stops short of describing return format or pagination, but for a no-param read tool this is solid added value.

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?

Purpose is front-loaded in the first sentence, with the auth prerequisite cleanly separated in a second paragraph. Slightly verbose in the parenthetical routing hint ('Claude Code: /mcp → Authenticate'), but no sentence is wasted.

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, read-only tool with no output schema, the description covers purpose, scope of returned statistics, and the authentication gate. The only gap is not describing the shape of the statistics response, which is minor given the tool's simplicity.

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 zero parameters, which is the baseline-4 case per the rubric. There is nothing to document, and the empty schema is consistent with the description's summary-only framing.

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 and resource ('Get webhook delivery statistics') and enumerates the contents (total deliveries, success/failure counts, recent activity). It is clearly a read-only summary tool, though it does not explicitly differentiate itself from sibling tools like list_webhook_deliveries or get_webhook_delivery.

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 ACCESS paragraph gives a concrete precondition (Proof account + authenticate) and even notes that start_login does not unlock this tool, which is useful routing guidance. However, it never says when to choose this stats tool over the sibling list_webhook_deliveries or get_webhook_delivery, so usage relative to alternatives is only implied.

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