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

Annotations already establish read-only, idempotent, non-destructive, closed-world behavior, so the description adds useful context rather than carrying the full burden. It adds that the tool returns plan-gated settings and the required plan for each, and clarifies the boundary between general greeting/auto-trigger bubbles and Proactive Messages. It does not add auth, rate-limit, or detailed response-shape information, but those are less critical given the rich 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?

Three tight sentences, front-loaded with what the tool returns and what categories of settings are included. The third sentence earns its place by preventing confusion between general widget settings and Proactive Messages.

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?

With one optional parameter, rich safety annotations, and no output schema, the description provides enough return-value context: all appearance and behaviour settings plus plan-restricted settings and required plans. An agent can call it correctly and understand the main content of the response without further output documentation.

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%: website_id is documented as coming from list_websites and omittable to use the primary website. The description only refers to 'one website's chat widget' and does not add syntax or format detail beyond the schema, so the baseline 3 applies.

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 uses a specific verb and resource: 'Read all appearance and behaviour settings for one website's chat widget'. It also distinguishes the scope from Proactive Messages by naming list_proactive_messages, and the read-only framing contrasts with update_widget_settings.

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 context for when to use the tool: reading all widget appearance and behaviour settings for a website. It explicitly routes click/page/time/event messages to list_proactive_messages, but does not explicitly say when to use update_widget_settings instead for mutations or list_widget_translations for translations.

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