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

No annotations are provided, so the description carries the behavioral burden. It explicitly states 'Read-only' and clarifies that the data is the public inventory figure shown on the SparkAds landing page, signaling safety and public scope. It does not detail auth or rate limits, but this is a zero-parameter read-only tool, so the disclosed behavior is sufficient.

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 tightly written sentences with no filler. The first sentence sets the operation and lists the outputs, and the second clarifies scope and read-only semantics. Every phrase adds value.

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?

For a parameterless read-only tool with no output schema, the description fully covers the needed context: time window, metrics returned, public vs. advertiser scope, and safety. Nothing an agent needs to select and invoke this tool 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?

The tool has zero parameters secret, so the schema is vacuously fully described. The description appropriately does not waste space on parameter details, and the baseline of 4 applies for parameterless tools.

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 names a specific operation ('Get the whole network's last 24 hours') and enumerates the exact metrics returned. It also distinguishes itself from advertiser-specific stats by stating it is the public network figure, not the advertiser's own numbers, making it clearly separable from siblings like get_my_stats.

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 description makes the use case clear: retrieving public network-wide inventory metrics for the last 24 hours. It implicitly tells the agent not to use this when advertiser-specific numbers are needed, but it does not explicitly name an alternative tool or provide when-not-to-use guidance.

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