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

With no annotations, the description carries the full burden. It discloses that the operation is free and requires no wallet, suggesting a non-mutating informational action. However, it does not explicitly state that it does not execute the service, only that it gives a 'preview', and it omits any potential side effects or error behavior. The transparency is decent but not exhaustive.

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 a single, front-loaded sentence that covers the essential points: free, representative preview, exact price, upgrade instructions, and no wallet requirement. Every phrase adds value, with zero wasted words. It is ideal for quick agent comprehension.

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 one parameter with a large enum, no output schema, and no annotations. The description explains what it returns (preview, price, upgrade instructions) and that it targets paid services. It does not mention error handling or output format, but given the informational nature, it is largely sufficient for an agent to invoke it 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?

The schema has 0% description coverage, so the description must add meaning. It clarifies that the 'service' parameter selects a paid service from the enum. However, it does not elaborate on what each enum value represents or how to choose between them. Given the long list of services, this is a minimal but helpful clarification.

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 states a clear purpose: providing a free preview, exact price, and upgrade instructions for any PHION paid service. It explicitly notes that no wallet is required, distinguishing it from tools that execute actual paid transactions. The verb 'provide' and resource 'preview, price, upgrade instructions' make the action specific.

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 does not provide explicit guidance on when to use this tool versus the many service-specific siblings (e.g., payment_preflight, attest). It implies generic applicability ('any PHION paid service') but lacks a clear 'use this when...' or 'use that instead...' instruction, leaving the agent to infer the appropriate choice.

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