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

With no annotations, the description carries the full burden, and it does disclose one genuinely important trait: the signing secret is returned 'ONCE' and is presumably unrecoverable. However, it says nothing about auth/permission requirements, whether the endpoint becomes active immediately, or how duplicate URLs are handled.

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 tight sentences, front-loaded with the action and followed by the critical return-value warning. No filler, though the brevity leaves obvious gaps that other tools would have covered.

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?

A creation/mutation tool with no annotations, no output schema, and only 25% schema description coverage needs substantial description support. The one-time secret warning is helpful, but auth requirements, event semantics, and side effects are all missing.

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 only 25% (only url is documented), so the description is obliged to compensate and does not. It never explains app_id, events, or label, nor the meaning of the whsec_ prefix relative to inputs.

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: 'Register a new webhook endpoint.' This is clearly distinguishable from the list-style siblings pax.webhook_endpoints_list and pax.webhook_deliveries, though the description never names or contrasts them explicitly.

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 gives no when-to-use or when-not-to-use guidance, no prerequisites (e.g. app ownership, auth scope), and never points to the sibling endpoints for listing or inspecting deliveries. Usage is only implied by the verb.

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