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

Annotations only say destructive/non-idempotent/open-world; the description adds the money that gets spent ($5 card, $0.03 from agent balance), that no account or sign-in is needed for the user, that orderToken is shown once and is the sole proof of purchase, that the order must be completed via appraisal_order_status, and that undeliverable paid orders are fully refunded. That is exactly the extra context the annotations cannot carry, and nothing contradicts them.

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 with the action, price, and trigger condition, then flows naturally into pricing variant, return values, and the follow-up call. Dense and nearly waste-free, though the inline documentation URL and the pricing paragraph make it longer than strictly necessary for a one-parameter tool.

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?

Covers the full lifecycle an agent needs: when to call, what it costs, what comes back, what to hand the user, what to retain, which tool to call next with which arguments, and the refund fallback. Even though an output schema exists, the explicit workflow handoff to appraisal_order_status closes the loop that a schema cannot.

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 is a single parameter with 100% schema description coverage, so the schema already defines 'domain'. The description adds only mild meaning — that the appraisal must be fresh and computed on this server, which implies the domain should be one that isn't already appraised — but no format or validation detail beyond the schema's own example. Baseline 3 applies when the schema does the heavy lifting.

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 with scope and price: 'Buy a fresh appraisal of one domain, computed on this server, for $5 by card.' It also implicitly distinguishes itself from appraise_domain (which returns notAppraised) and from the agent-account pricing path, so an agent can tell it apart from the several sibling purchase/status tools without opening a schema.

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?

Explicit triggering condition: 'Use it when appraise_domain answered notAppraised and the user wants the figure returned to you rather than opened in their browser' — that sentence both names the alternative and the condition that selects this tool. It further routes the agent to the cheaper agent-account path when an operator-funded balance exists, which is a genuine alternative, not just a caveat.

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