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

Annotations cover safety (readOnly=false, openWorld=true, idempotent=false, destructive=false), but the description adds behavior annotations cannot express: the two-step confirmation flow, the plan/scope prerequisites, and the one-time signing-secret disclosure. That one-time secret warning is genuinely useful operational context.

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?

Four short sentences, front-loaded with the confirmation requirement and the outcome before the prerequisites. Each sentence carries distinct information (what it does, prerequisites, secret handling), with only slight redundancy around the event destination.

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 5-parameter mutation with no output schema, the description covers the confirmation protocol, auth/plan requirements, and secret handling – the high-risk aspects. It falls short only on minor parameter semantics for label/categories, which is a modest gap rather than a blocking one.

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 40%, and the description fills in some of the gap by confirming that events are delivered to the URL and that a signing secret is issued. However, it says nothing about 'label' or 'categories', leaving two parameters undocumented in both places.

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 gives a specific verb+resource ('Register a webhook on the user's account') plus the effect ('Listing events will be sent to this URL'), so the agent immediately knows what the tool creates and where the payloads go. It does not need sibling differentiation because no sibling tool touches webhooks.

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?

It states the gating conditions clearly: explicit user confirmation, Pro (including free trial), and the write:account scope. It does not discuss when to prefer an alternative, but there is no plausible alternative in the sibling list, so the context is unambiguous.

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