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

Annotations only mark it as non-read-only, non-idempotent, non-destructive. The description adds real behavioral context beyond that: it requires the user's OPN account (sign-in or API key) and consumes 1 Suite run, and it reads live PackIndex values rather than cached data. It stops short of saying whether the run is spent on failure or what happens if neither input is supplied.

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?

Two tight sentences with zero filler; the core action and its scope lead, followed by the operational prerequisites. Nothing is repeated from the title or annotations.

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 non-idempotent, run-consuming tool with no output schema, the description covers what it produces (a BOM anchored to live indices), the auth requirement, and the cost. It is nearly complete, missing only edge-case behavior such as error handling or whether both optional inputs can be passed together.

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 the spec-object alternative to project_id but adds no format, precedence, or mutual-exclusivity detail beyond what the schema already provides for these two params.

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 and resource: 'Derive the bill of materials for a Design Studio project (or a spec object)' and clarifies it anchors components to live PackIndex values. This is meaningfully distinct from siblings like draft_packaging_spec or estimate_packaging_price, though it never names those alternatives to sharpen the boundary.

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?

Usage is only implied: the schema note 'From draft_packaging_spec' suggests drafting precedes costing, but the description itself gives no explicit when-to-use or when-not-to-use guidance versus the pricing/estimation siblings. It does surface the precondition (OPN account) and cost (1 Suite run), which is useful context.

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