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

Annotations already declare a non-idempotent, non-destructive, non-read-only write with no open-world access. The description adds two real behavioral facts beyond that: the target URL must be 'allowlisted' (a precondition/workflow constraint) and deliveries are 'signed' (implying a signing secret is involved). It still omits permissions required, what happens on duplicate subscriptionKey, and what is returned.

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 front-loaded sentence with no filler; 'owner-scoped allowlisted signed' are all load-bearing qualifiers. It is dense but not padded, though the terseness trades away useful detail.

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?

There is no output schema, so the description should say what is returned (e.g., the subscription id and signing secret) and whether the secret is shown only once. It also omits prerequisites such as admin scope or URL allowlisting steps, leaving an agent short of what it needs to call this correctly.

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% and all three parameters (subscriptionKey, url, eventTypes) carry no descriptions. The description hints that 'url' must be allowlisted but says nothing about the meaning or format of subscriptionKey or the eventTypes enum values, so it fails to compensate for the coverage gap.

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?

Specific verb ('Create') plus resource ('webhook subscription') with qualifiers 'owner-scoped' and 'signed'. An agent can distinguish it from evidence_list_webhooks, evidence_set_webhook_status, and evidence_rotate_webhook_secret, though the description never names those alternatives 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?

No when-to-use guidance, no exclusions, and no routing to siblings such as evidence_send_webhook_test or evidence_set_webhook_status. The reader is left to infer that this is the entry point for registering a new subscription.

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