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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds real context beyond that by disclosing the shape of the response (plan, dates, gated capabilities, quota used/left) and the gating semantics between plan and readable resources. It stops short of describing failure modes or whether quota values are point-in-time, but the meaningful behavioral content is there.

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 sentences, front-loaded with what is returned, then the usage trigger, then the hand-off to siblings. Every sentence carries distinct information and nothing is repeated from the title or annotations.

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 full burden of explaining the return value, and it does so by naming the four categories of content (plan, dates, gated reads, quota consumption). An agent knows what it will learn and what it will not get (the item lists behind the counts) from this text alone.

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, so there is nothing for the description to disambiguate and the baseline is 4. The description correctly implies a single implicit account scope rather than introducing any argument semantics.

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 and resource and then enumerates the actual payload: plan, its dates, the gated reads it opens (capabilities, sales_feed), and quota/limit consumption. It also names the sibling tools (list_views, list_watchlist, list_destinations) that handle the underlying items, so an agent can distinguish it from the list_* family 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?

Gives an explicit trigger ("when the person asks about their plan or usage") plus a precondition ("before saying which plan includes a reading"), and explicitly routes the drill-down case to list_views, list_watchlist or list_destinations. Both when-to-use and when-to-use-something-else are covered.

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