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

Annotations only say readOnlyHint=false, openWorldHint=false, destructiveHint=false. The description adds valuable behavior: paid two-step x402 flow, wallet ownership, public readability, expiry return, receipt location, and auth requirements. This is consistent with readOnlyHint=false and adds substantial context beyond 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 core content is dense and front-loaded with the PAID nature and return value, but the closing feedback paragraph ('Complaints, questions, quote requests...') is off-topic for tool selection and invocation. It adds roughly a quarter of the text without helping an agent use the tool correctly.

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?

Despite having no output schema, the description covers the full call sequence, return values (object id and expiry), payment keys, ownership/readability model, and auth requirements. An agent has enough information to invoke this complex paid mutation correctly.

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% and each parameter already has a description. The tool description adds meaning by linking plan to size/price, requiring decoded base64 size to fit the plan, and explaining the payment-related meta keys. That exceeds the baseline for fully-documented 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 action and resource: 'store opaque bytes for the life of the plan you buy', qualified by PAID. It also differentiates from siblings by pointing to storage_read for retrieval and storage_renew for extension, so an agent can tell it apart without opening tool schemas.

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?

Gives explicit usage steps: call once without payment to receive the price, then call again with a signed payment in _meta['x402/payment']. It also names the right siblings for follow-up operations and notes that no account or API key is needed.

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