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

Annotations already declare readOnlyHint=true, so safety is covered. The description contributes one genuinely useful behavioral fact beyond the schema: the Advance plan key requirement, which would otherwise cause a failed call. It says nothing about aggregation window, caching, or what 'plan usage' includes.

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 short sentences with no padding, and the blocking prerequisite is front-loaded where an agent will see it first. The second sentence is a bare fragment rather than a complete clause, which slightly hurts readability but not economy.

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 no parameters and no output schema, the description carries the whole burden of explaining the return. It names the four data categories but not the time range, granularity, or shape of the 'overview', which an agent needs to decide whether this answers its question.

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?

The tool takes zero parameters and the input schema is an empty object, so there is nothing for the description to disambiguate. Baseline 4 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 is a noun list — 'Messages, conversations, automations and plan usage overview' — with no verb, so the agent must infer that this returns aggregated dashboard statistics. It does hint at an aggregate rather than a list, which loosely separates it from siblings like list_conversations and list_automations, but that distinction is never made explicit.

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?

The only guidance is a prerequisite ('Requires an Advance plan key'). There is no statement of when to reach for this aggregate view versus calling list_conversations, list_automations, or get_otp_usage individually, and no exclusions.

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