ebay_create_ad_by_listing_id

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

Annotations only provide readOnlyHint=false, which signals mutation but nothing else. The description does not disclose whether this creates a new ad, overwrites an existing ad, requires a campaign to be active, or what happens on duplicate listing IDs. It also does not mention any prerequisites like an opted-in program or existing ad group. For a mutation tool with minimal annotation coverage, the description carries the burden and does not meet it.

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 a single sentence with no filler. It front-loads the action and resource. It could add a bit more context about prerequisites or behavior without becoming bloated, but as written it is efficient.

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 mutation tool with no output schema and minimal annotations, the description is too thin. It does not explain the expected effect, prerequisites (e.g., campaign/ad group existence, eligibility), or how it differs from the many sibling ad-creation tools. An agent would need to inspect the schema and possibly the API docs 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?

Schema description coverage is 100%, so the schema already documents campaignId and the request body. The description adds no parameter-level meaning beyond the schema, but the baseline of 3 applies because the schema does the heavy lifting. The nested request object's fields (adGroupId, listingId, bidPercentage) are self-descriptive in name but lack format details such as whether bidPercentage is a string percentage or decimal.

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 ('Create') and resource ('ad by listing id') and names the API ('eBay Marketing API'). It is clear enough to distinguish from bulk variants like ebay_bulk_create_ads_by_listing_id and from ebay_create_ads_by_inventory_reference, though it does not explicitly name those siblings.

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 implies this is the single-ad creation path by listing ID, and the sibling list shows bulk alternatives, but it does not explicitly state when to use this tool versus ebay_bulk_create_ads_by_listing_id or ebay_create_ads_by_inventory_reference. An agent can infer the usage context from the name and schema, but there is no direct guidance.

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