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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true. The description adds useful behavioral context by mentioning pagination, filters, and the structure of each delivery (endpoint and nested email object), which goes beyond the annotations.

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 long, front-loaded with the core functionality, and includes a practical use case. Every word serves a purpose with no redundancy.

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?

Given that the tool has an output schema (so return structure is not needed in description), strong annotations, and 6 optional parameters, the description covers the key aspects: purpose, what each delivery contains, and a primary use case. It is slightly lacking in explaining pagination details like the cursor usage, but the schema parameters already cover that.

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 description coverage is 100%, so the baseline is 3. The description mentions 'pagination and filters' which vaguely relates to parameters, but it does not add specific parameter-level meaning beyond what the schema already provides.

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 action ('List webhook delivery attempts') and the resource ('webhook deliveries'). It specifies pagination and filters, and distinguishes from siblings like listEmails or listEndpoints by focusing on delivery attempts with nested email objects.

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 a clear use case ('diagnosing delivery failures or confirming a specific email was delivered'), giving context for when to use the tool. However, it does not explicitly mention when not to use it or name alternative tools like replayWebhookDelivery.

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