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

With no annotations, the description carries the full burden. It discloses the return structure in detail (deliveries array with fields, total, success_rate) and provides an example, which goes beyond schema to explain behavior. It does not mention side effects (likely none) or auth requirements, but for a read-only tool this is adequate.

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 well-organized into a one-line summary, WHEN TO USE, RETURNS, and an EXAMPLE. Each section adds value without redundancy and it is appropriately sized for the tool's complexity.

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?

Despite having no output schema or annotations, the description compensates by thoroughly explaining return values, usage context, and providing an example. It covers the essential operational details an agent needs to invoke the tool effectively.

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?

Schema coverage is 100% with descriptions for all three parameters. The description adds an example with realistic values but does not significantly expand on parameter meaning beyond what schema already provides. Therefore the baseline of 3 applies.

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 'Get delivery history for a webhook' with a specific verb and resource. This distinguishes it from siblings like list_webhooks and test_webhook, which serve different purposes.

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 'WHEN TO USE' section lists concrete scenarios (debugging failed deliveries, auditing activity, checking success rates), providing clear context. It does not explicitly exclude alternatives or mention when not to use, but the context is sufficient for selection.

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