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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description still earns credit by disclosing a non-obvious degraded state — data comes back null and payload_withheld is true when the caller lacks read access to the event's resource — which is exactly the kind of authorization-driven behavior an agent cannot get from 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?

Two sentences, no filler. The returned-content summary leads and the edge-case state follows, so the most decision-relevant information is front-loaded.

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?

An output schema exists, so return-value documentation is not strictly required, and the description still sketches the response shape and the withheld-payload case. What's missing is the relationship to sibling webhook tools, which is the only real gap for a one-parameter read tool.

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?

Single required parameter with 100% schema coverage, and the schema already gives examples (test_event_id, event_id). The description adds no further meaning about event_id, so the baseline 3 applies rather than a higher score.

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 ('Gets one webhook event') and enumerates what comes back: the payload plus each destination's delivery status and HTTP attempts. That distinguishes it from get_webhook (the webhook config) in substance, but the description never names that sibling explicitly, leaving the agent to infer the split from the resource noun alone.

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?

There is no statement of when to reach for this tool versus get_webhook, list_webhooks, or send_webhook_test_event. The only conditional clause ('when you can't read the event's resource') describes a runtime state, not a selection criterion, so routing must be inferred entirely from the tool name.

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