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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the "Read-only" sentence is largely redundant. Beyond that, the description adds real behavioral context: the data window is the last 24 hours, the figures are network-wide public inventory, and the same values published on the SparkAds landing page. It doesn't say how fresh the snapshot is or how the hourly-slot count is computed, which keeps it below a 5.

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, front-loaded with the scope and metric list, with the disambiguation to advertiser stats placed before the throwaway closing note. The final "Read-only." fragment duplicates readOnlyHint and is the one piece of dead weight.

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?

There is no output schema, so the description carries the burden of describing return values — and it does so explicitly, naming all four figures the caller will receive. For a zero-parameter read tool, nothing an agent needs to invoke it correctly is missing.

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?

With zero parameters, the baseline is 4; there is no input semantics to clarify. The description instead pre-explains the semantics of the metrics being returned (impressions, clicks, carousel adoption, hourly coverage), which is useful but belongs to output rather than parameter meaning.

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 ("Get") and scope ("the whole network's last 24 hours") and enumerates the exact metrics returned: total impressions, total clicks, carousel app count, and occupied hourly slots. It also explicitly distinguishes this network-wide figure from the advertiser-scoped numbers that sibling get_my_stats would provide, so an agent can route correctly 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?

It gives clear selection context: use this for the public inventory figure shown on the SparkAds landing page, not the advertiser's own numbers — which implicitly points away from get_my_stats. What's missing is naming the alternative tool outright, so the routing is inferred rather than stated.

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