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

With no annotations provided, the description carries the full responsibility for behavioral disclosure. It implies a read-only operation ('get') and states the access prerequisite, but it does not elaborate on whether the tool is idempotent, what scopes are needed, or how 'recent activity' is time-bounded. This is acceptable but not comprehensive.

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 two sentences, with the main purpose front-loaded. The second sentence contains essential access instructions but is somewhat verbose; it could be tightened without losing information. Still, every part earns its place, and there is no padding.

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 tool with no parameters and no output schema, the description is reasonably complete. It states what the tool returns and the required authentication. It does not specify the output format, but since no output schema exists, the description provides a sufficient overview for a correctly invoke.

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 has zero parameters, so the schema coverage is vacuously 100%. Per calibration, 0 parameters merits a baseline of 4. The description adds useful detail about the kind of statistics returned (total, success/failure counts, recent activity), which enhances understanding beyond the empty schema.

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 clearly states the tool's purpose: 'Get webhook delivery statistics including total deliveries, success/failure counts, and recent activity.' It names a specific verb and resource, and the phrase 'statistics' differentiates it from sibling tools like get_webhook_delivery or list_webhook_deliveries, though not explicitly.

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 provides concrete usage context: it requires a Proof account, instructs the user to authenticate before calling, and explicitly warns that 'start_login does NOT open this tool,' which is a useful exclusion. However, it does not mention alternative tools for individual delivery details, so some room remains.

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