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

With no annotations, the description carries full burden for behavioral disclosure. It only says "for testing," implying a non-production use, but does not explicitly state it is read-only, mention permission requirements, or note any side effects or limitations. The return values are described, but not the behavior.

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?

The description is well-structured with clear sections: overview, WHEN TO USE, RETURNS, and an EXAMPLE. Each section adds value without excessive verbosity, though the formatting is a bit longer than strictly necessary.

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 simple one-parameter tool with no output schema, the description covers purpose, usage scenarios, return fields (ads, default_stream, schedule), and provides an example. It is complete enough for an agent to understand and invoke the tool, though it omits edge-case behavior.

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 coverage is 100% with a clear description of the fingerprint parameter. The description also includes an example usage that reinforces the parameter. However, it does not add meaning beyond what the schema already provides, so baseline 3 is appropriate.

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 clearly states a specific verb+resource: "Get current ads scheduled for a device (for testing)." This distinguishes it from the many sibling get_* tools by explicitly focusing on device ads, and the parenthetical "for testing" adds useful context.

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?

A dedicated "WHEN TO USE" section lists three concrete scenarios: testing device ad delivery, debugging which ads are shown, and verifying ad targeting. This provides clear context, though it does not mention when not to use the tool or suggest alternatives.

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