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

Annotations already declare destructiveHint=true and readOnlyHint=false, but the description adds materially more: the exact permission needed, the in-flight delivery semantics ('deliveries stop after the current attempt'), and the 404 behavior for foreign or already-deleted IDs. Those are precisely the facts an agent needs before executing an irreversible operation, and none are derivable from the schema or annotations.

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 sentences, zero filler. The effect of the deletion is front-loaded, and the permission and error semantics follow as compact clauses rather than prose.

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 single-parameter destructive tool with an output schema and full annotation coverage, the description covers the remaining gaps: authorization, timing of the delivery cutoff, and the 404 ownership case. Nothing an agent needs in order to call it correctly is absent.

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% for the single endpoint_id parameter, so the description must carry the load, and it does: it establishes that the ID is scoped to the caller's own merchant account and that non-owned or deleted IDs return 404. It stops short of stating the ID format or where to obtain one (presumably webhook_set/webhook_list), which keeps it from a 5.

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 pairs a specific verb ('Delete') with a specific, scoped resource ('one of your webhook endpoints'), making it trivially distinguishable from sibling tools like shop.merchant.webhook_set and shop.merchant.webhook_list, which operate on the same resource with different verbs.

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 gives clear conditions: requires the webhooks:write scope, and only endpoints you own can be targeted. What is missing is an explicit routing statement naming the alternative (e.g. 'to create or update an endpoint, use webhook_set'), so an agent must infer the sibling boundary from the verb alone.

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