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

Beyond the readOnly/openWorld/destructive annotations, it discloses several non-obvious traits: imageUrl/videoUrl links expire in ~1 day, creative lookups are cached ~1 day, stores with enriched: false return no ad data, and calls are metered once per store per month. These are exactly the cost, freshness, and data-availability caveats an agent needs before invoking.

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?

Front-loaded with the data domain, then the conditional creative mode, then freshness/metering caveats — every sentence carries information. It is dense and slightly run-on in the first sentence, but nothing is padded.

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 carries the full burden and delivers: it enumerates returned fields, explains the two response modes, and covers caching, link expiry, enriched:false emptiness, and metering. An agent has everything needed to call and interpret this tool.

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 description coverage is 100%, so the baseline is 3. The description reinforces that omitting platform changes the return shape and that limit bounds creatives, but this largely restates the schema's own platform and limit descriptions rather than adding format or constraint detail.

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 states a specific verb+resource (store advertising activity) and precisely enumerates both return modes: cross-platform presence (active, ad count, estimated monthly spend) and per-platform creatives with named fields. It distinguishes itself from siblings by noting it is "metered like get_store", signalling a different data domain than get_store_email or list_store_technologies.

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 conditional usage: specify platform to get actual creatives, omit it for the presence summary only, and it names the metering sibling get_store for cost comparison. It stops short of explicit when-not-to-use guidance against the other eight siblings, so it is clear context rather than full routing.

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