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

With no annotations, the description carries the full burden and does well: it discloses the $0.02 USDC cost, that returns are x402 payment requirements, and that the agent's wallet executes payment. This is critical behavioral context beyond structured fields. It stops short of describing what happens if payment fails or any rate limits.

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?

Front-loaded purpose, then cost/payment behavior, then a concrete example. Every sentence earns its place and the example format is 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?

For a 2-param tool with an output schema present, the description covers purpose, cost, payment flow, and an example. It doesn't need to explain return values (output schema exists) and is nearly complete, though it could mention error/edge-case behavior for a payment-gated tool.

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 0%, so the description must compensate. It clarifies that title is the product title to parse and price is optional package price, and the example shows expected formats (title="... 2lb", price="$29.99"). This adds real meaning but doesn't fully document format expectations or edge cases for both parameters.

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 (parse/resolve) and resource (product title into pack count, unit size, unit price). 'Pack-size resolver' plus the enumerated outputs makes the purpose unambiguous and distinct from siblings like list_packs or buy_pack.

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 implies when it's used (resolving pack size from a title) and the example clarifies the calling context. However, it gives no explicit when-to-use vs alternatives guidance and doesn't clarify the relationship to sibling tools like list_packs or buy_pack, so usage is only implied.

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