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

Annotations already establish that this is a safe, idempotent, non-destructive read, so the description only needs to add scope. It does that well by bounding the content to credits and the published list price and explicitly stating it does not report campaign run costs, which prevents a costly misread of the numbers returned.

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 definition is short and front-loaded with the core action, followed by the return shape and scope limits. The last two sentences could be merged into one, but the negative constraint earns its place.

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 output schema, the description supplies the returned field names, which is exactly the compensation needed. Combined with annotation coverage and a single trivial optional parameter, an agent has enough to call it correctly.

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 single parameter, response_format, has an enum of markdown/json but zero schema description coverage and is not mentioned in the description. The enum is largely self-explanatory, so this is a minor gap rather than a blocking one, but the description adds no meaning about when to prefer each format.

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: shows the signed-in user's Ad Run credit balance and whether they can start a new Ad Run. It is clearly distinct from list/get Ad Run siblings by being account-level, though it never explicitly contrasts itself with idealaunch_get_capabilities, which could plausibly overlap.

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 'whether they can start a new Ad Run' phrasing implies the tool is a pre-flight check before idealaunch_prepare_ad_run, but that is inferred rather than stated. There is no explicit when-to-use, when-not, or named alternative.

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