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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the write/non-idempotent profile is covered structurally. The description adds only 'HTTPS' as a hard requirement, and its claim of configuring 'retry settings' is not backed by any retry parameter in the schema, which risks misleading the caller; it never warns that the non-idempotent create can produce duplicate endpoints on retry.

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 compact sentences with the core action front-loaded and no filler. Sizing is appropriate for a create tool, though the trailing 'using the requested customer and URL' is mildly redundant.

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 mutating tool with 6 parameters, 0% schema coverage, no output schema and no annotations explaining auth or permissions should do substantially more. The description leaves half the parameters unexplained and omits any statement of what is returned or what happens to existing subscriptions.

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 0%, so the description must carry parameter meaning. It only gestures at three of six parameters (recipient as 'customer', url, eventTypes as 'event subscriptions') and never explains appId, name, or recipientName; the referenced 'retry settings' parameter does not exist in the schema.

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 (Add) and resource (HTTPS webhook endpoint) scoped to a customer of an outbound app, which separates it from generic siblings like create_destination or create_source. It is clear what the tool produces, though it never explicitly contrasts itself with update_endpoint or ensure_webhook_setup.

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 prerequisites, and no mention of alternatives such as update_endpoint (for existing endpoints) or ensure_webhook_setup. The agent learns what the tool does but not when it is the right choice among 50+ siblings.

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