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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered without description help. The description adds a small amount of context the annotations do not: the cost signal "API calls: 1" and the fact that plan-level live-delivery eligibility is included in the response. It says nothing about pagination, empty-account behavior, or whether newly created inboxes appear immediately.

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?

A single compact sentence with the resource front-loaded, plus a terse cost note. Nothing is padded, though the fragment form ('API calls: 1') reads like boilerplate rather than a sentence earning 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?

With an output schema present and zero parameters, the description does not need to explain return values or arguments, and the safety profile is carried by annotations. What remains missing is the routing information an agent needs inside a crowded webhook tool family — specifically why to pick this over list_webhooks or the inbox mutation tools.

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 takes zero parameters, so there is nothing for the description to disambiguate; the baseline for a parameterless tool applies. No misleading or missing parameter guidance exists.

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 identifies the resource ("this account's live test inboxes, their limits and whether the plan includes live delivery"), so the agent can infer it returns inbox configuration data. But it is a noun phrase with no verb and no differentiation from adjacent tools such as list_webhooks, list_webhook_events, or read_webhook_inbox, all of which touch webhook inbox/endpoint data.

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 guidance on when to call this versus list_webhooks, create_webhook_inbox, or read_webhook_inbox, and no stated preconditions. The agent must infer usage purely from the resource noun and the sibling names.

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