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

With no annotations, the description carries the full burden, and it discloses several useful behavioral traits: deliveries are signed, the secret is returned only once, missed deliveries do not lose data, and the inbox remains the authoritative record. It does not cover idempotency, overwrite semantics, or authorization, but it goes well beyond a bare CRUD description.

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 and front-loads the core behavior, then adds the optional scoping, the one-time secret, and failure semantics. Every sentence earns its place, and nothing is redundant or padded.

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 no output schema and no annotations, the description does well to mention the one-time secret and the persistence of inbox events. It is not fully complete for invoking the tool correctly because the required owner parameter remains unexplained and there is no mention of overwrite or deletion semantics. Still, an agent would understand the main purpose and key failure behavior.

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 0%, so the description must compensate. It explains url as the delivery endpoint for signed inbox events and taskId as optional scoping to one task. However, the required owner parameter is never explained, leaving a meaningful gap for a mandatory argument.

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 identifies the action: leave a URL and the hub starts posting signed inbox events to it. This distinguishes set_webhook from siblings like list_webhooks and forget_webhook by describing the registration/subscription behavior rather than listing or removing hooks.

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 explicitly frames this as the alternative to polling: 'instead of you polling for them.' It also clarifies the optional task-scoping use case. It does not name a specific fallback tool or state when not to use it, but the context is clear enough for an agent to choose it appropriately.

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