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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered; the description adds meaningful context the annotations lack - the account-owner-only authorization requirement and the fact that the new endpoint URL must be confirmed by the owner. It never states whether the events array replaces or appends to the existing subscription set, which is the main behavioral gap left.

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?

Three short sentences, zero padding, with the core action front-loaded before the tool-routing and permission constraints. Every sentence carries information the agent needs.

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?

An output schema exists and annotations cover safety, so the description only needs to add scope and constraints, which it largely does. However, for a destructive replacement-style update it leaves the replace-vs-append semantics of the events list unstated, which is the one thing an agent most needs before calling it.

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 100% and the schema itself explains each enum value and the delivered event naming convention, so the description adds no parameter-level meaning. Baseline 3 applies when the schema already does the heavy lifting.

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+resource: it selects which events a webhook endpoint receives, with a title reinforcing the same. It explicitly hands off a related but different operation (address changes) to change_webhook_endpoint_url, so an agent can distinguish it from siblings without opening a schema.

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?

Names the alternative tool for the adjacent operation (changing the URL) and states the authorization precondition (account owner's API keys/connected apps only). It does not spell out when to prefer this over create_webhook_endpoint or delete_webhook_endpoint, but the context is clear.

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