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

readOnlyHint=true already tells the agent this is a safe read, so the description's burden is lower. It adds that results include HTTP outcomes, which is useful context, but says nothing about ordering, pagination limits, or retention windows. Adequate but not rich given the annotation coverage.

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?

One tight sentence plus a routing endpoint notation; the diagnostic hook is front-loaded and nothing is redundant. Every clause earns its place.

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 read-only list tool with seven fully documented optional parameters and a readOnlyHint, the description is nearly sufficient, and 'with their HTTP results' gives a hint about return contents despite no output schema. It could still note that results are paginated for the agent to page through.

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 all seven filters (succeeded, event_type, endpoint_id, timestamps, paging) are already documented in the schema itself. The description adds no filter semantics, so the baseline 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?

States a specific verb and resource ('list webhook delivery attempts') and adds the diagnostic framing 'why did my webhook not arrive?', which separates it in spirit from the sibling polar_list_webhook_endpoints. It stops short of explicitly naming the sibling it is not (endpoints vs. deliveries vs. redeliver), so it is clear but not fully differentiated.

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 quoted user question ('why did my webhook not arrive?') gives a concrete when-to-use context, which is more than most list tools provide. However, no alternatives or exclusions are named — e.g. it never points to polar_redeliver_webhook_event for retrying a failed delivery.

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