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

Annotations already declare readOnlyHint/openWorldHint/destructiveHint=false, so safety is covered; the description still earns credit by adding that no credits are spent and no I/O occurs — non-obvious in an API where other tools charge credit prices. It also previews the record contents, though that overlaps with the output schema.

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?

One front-loaded sentence that leads with the resource and then the consuming tool. It is a long run-on that enumerates return fields already documented by the output schema, which slightly dilutes efficiency without adding an agent-relevant decision.

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 annotations and a full output schema already present, the description only needs to explain purpose and placement in the workflow — it does both. Its detailed field-by-field enumeration is largely redundant with the output schema, but nothing an agent needs in order to call 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?

Zero parameters, so the baseline is 4 and there is nothing to disambiguate. The description usefully references the `slots` parameter of a different tool, giving the agent the linkage between this call's output and where it is consumed.

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 ("List the ad formats") and immediately scopes it to the formats generate_ads_from_url accepts in `slots`, which ties it unambiguously to the sibling that consumes this data. An agent can distinguish this discovery tool from list_* siblings without opening any 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?

By naming generate_ads_from_url and its `slots` parameter, the description makes the use case clear: call this to learn valid format ids before invoking the generator. It stops short of an explicit "call this before/after" instruction or naming a competing discovery path, so it is clear context rather than full when/when-not guidance.

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