union_product

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

In the absence of annotations, the description does add useful behavioral context: the inputs are primary keys, and the result is 'reloaded for this session,' implying session-local state. However, it does not clarify whether the operation mutates session state, what the return value is, or whether anything is persisted, leaving important risk factors ambiguous.

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, front-loaded sentence with no filler. It states the operation first, then the input identification method, then the session scope. Every word carries meaning.

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 tool with no annotations and no output schema, the description leaves out the return value and the exact side effects of 'reloaded for this session.' An agent cannot confidently know whether calling union_product returns the merged set, updates a session, or overwrites existing state. The core input semantics are covered, but the overall contract is incomplete.

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?

With 0% schema description coverage, the description compensates meaningfully by explaining that both `left` and `right` arrays are Product sets identified by primary keys. Without this, the schema alone would suggest only 'arrays of strings.' It could still be more precise about key format or duplicate handling, but the essential semantic gap is closed.

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 identifies a specific operation ('union') applied to a specific resource ('Product sets'), which distinguishes it from sibling operations like intersect_product, subtract_product, and union_customer/order/note. It also adds that the sets are identified by primary keys, so the scope is unambiguous.

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 usage is implied: an agent would choose this tool when it needs to union two product sets. However, the description gives no explicit guidance about when to prefer it over alternative set operations or where the input product sets would come from, and it does not mention any exclusions.

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