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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is known. The description adds substantial behavioral context: the meaning of `period` (monthly standing order vs one-time), that `stripe_price_id` is informational and never to be passed back, the graded pricing rule, and that only sellable records are billed. No contradictions with annotations.

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 longer than average but well-structured, moving from purpose to fields to pricing to alternatives. Every sentence carries information; there's no fluff. However, it could be more concise by separating the pricing rule into a supplementary sentence, yet as is it's efficient for the complexity it covers.

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 there is no output schema, the description fully covers the return fields (`product_id`, `name`, `description`, `state`, `lead_count`, `price_cents`, `period`, `stripe_price_id`) and explains their semantics. It also explains the pricing model, when to use alternatives, and how to buy. For a zero-parameter read-only list tool, nothing essential is missing.

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?

There are zero parameters, so per the rubric the baseline is 4. The description doesn't need to document any input semantics because none exist; it focuses on output and usage, which is appropriate.

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 opens with a clear, specific statement: 'The pre-shaped shelf — ready-made business type × state lists.' It names the resource (shelf products), the verb (lists), and the structure (business type × state). It also differentiates from siblings by naming alternatives like list_starters and interpret_list, so an agent can tell them apart.

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?

Explicitly states when to use this tool versus alternatives: 'For a shape of your own, or to see live graded counts and the exact price before buying, prefer the buying journey: list_starters ... or interpret_list → quote_list → checkout_list.' It also gives the purchase path: 'To buy a shelf product as-is, pass its product_id to create_checkout.' This leaves no ambiguity about selection.

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