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

Annotations already declare idempotentHint/destructiveHint/readOnlyHint, and the description adds substantial value beyond them: the catalog:write scope requirement, the price bounds ($1.00..limits.max_order_usd), the single $0.01 is_test exception, and the fate of prohibited-category and instruction-like items (rejected[], flagged/hidden). This is unusually rich behavioral disclosure for a mutation tool.

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?

Three dense sentences, front-loaded with the create/update action and idempotency key before the edge-case rules. Most clauses earn their place, though the stacking of constraints makes it slightly heavy.

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?

An output schema exists and the description still names the key return signal (rejected[]), and annotations cover the safety profile; the auth, price, and moderation rules round it out. Missing only explicit routing against sibling merchant tools.

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 coverage is 100% for the single items parameter, so the baseline is 3; the description nonetheless adds semantics the schema lacks, notably idempotency keyed on sku, the per-item price constraints, and the is_test/category field behavior.

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 pair (create or update) and resource (products by sku), and the sibling set (catalog_delete, catalog_get, catalog_search) makes the upsert role unambiguous. An agent can distinguish it from read/delete siblings without opening a 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?

Conveys context (bulk upsert up to 500, idempotent by sku) and a prerequisite (catalog:write), but never says when to prefer this over catalog_delete or how to handle the delete path. Usage is implied rather than routed.

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