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

Beyond the annotations (readOnlyHint=false, idempotentHint=false), the description discloses critical behavioral traits: it creates a checkout link, charges nothing, requires a human to complete payment, and costs no documents. This goes well beyond the structured metadata and clarifies side effects and limitations.

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?

Every sentence earns its place: it starts with the core purpose, then highlights critical warnings, gives usage context, and ends with the document cost. The structure is front-loaded and the length is appropriate for the complexity.

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?

The tool has no output schema, but the description adequately explains the return type (hosted checkout URL) and covers the full flow: link creation, human confirmation, non-purchase side effects, and usage trigger. For a two-parameter tool, this is fully complete.

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?

The input schema already describes both parameters with full coverage, including key optionality and plan enum values with prices. The description adds some context about plan limits (2,500 vs 25,000 documents) but largely reiterates schema information. Thus the schema carries the semantic weight, and the description provides marginal extra value.

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 uses a specific verb and resource: 'Return a hosted checkout URL for upgrading an Attestwire key to a paid plan.' It also distinguishes the tool from siblings by detailing the plans (starter/scale) and emphasizing it only creates a link, not a purchase. This is unambiguous and unique among the sibling tools.

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 explicitly states when to use it: 'Use this when a key has hit its quota or the user asks to upgrade.' It also provides clear exclusions: 'THIS DOES NOT BUY ANYTHING' and 'You cannot complete the purchase and must not report it as completed.' This gives the agent firm guidance on when and how to invoke.

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