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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so safety is covered. The description adds valuable behavioral context: sorting by newest effective date, enrichment with product/variant, pagination, and filtering options. These are not available in the schema and help an agent understand the tool's behavior beyond safety.

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 two sentences with zero waste. The core purpose and scope are front-loaded, followed by a compact summary of pagination and filters. Every clause earns its place, making it highly 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?

Given the output schema exists, the description need not explain return values. It covers the listing scope, ordering, enrichment, pagination, and filter options. It does not mention timezone resolution for date filters, but the schema already handles that. Overall, it is complete for a list tool of this complexity.

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%, so every parameter already has a detailed description. The tool description summarizes pagination and filtering but adds no new semantics beyond a concise overview. Since the schema carries the full load, the description meets the baseline of 3 without adding extra depth.

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 clear verb ('List') and resource ('cost-of-goods-sold entries') with explicit scope ('for all items and variants') and a specific ordering ('newest effective date first'). It also mentions enrichment with product and variant, which distinguishes it from single-item tools like get_item_cogs. The purpose is unambiguous and distinguishable from 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 clearly indicates this tool lists all COGS entries, implying it is for broad queries rather than single-item lookups. However, it does not explicitly name alternatives (e.g., get_item_cogs) or state when not to use it. The context is implied but not made explicit, so an agent might need to infer the boundary.

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