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

Annotations already mark the tool as read-only, idempotent, and non-destructive. The description adds extra transparency by explicitly stating that no order is accepted, no checkout data is returned, and no external provider is called. This aligns with annotations and provides further behavioral context.

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, efficient sentence that front-loads the main action and includes clarifying details. Every phrase earns its place with no waste.

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?

Given the presence of an output schema (not needing return-value explanation), a single well-described parameter, and supportive annotations, the description covers all necessary aspects. It is complete for an informational tool with low complexity.

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 has 100% coverage with a clear description for the only parameter. The tool description does not add new information about the parameter beyond what the schema already provides, so it meets the baseline without extra contribution.

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 clearly states the verb 'Explain' and the resource 'machine-origin purchase prerequisites'. It explicitly distinguishes itself from siblings by listing what it does NOT do (accept orders, return checkout data, or call a provider), making its purpose distinct.

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 implicitly explains when to use the tool (to explain prerequisites) and clarifies that it is not for actual ordering. However, it does not explicitly contrast with sibling tools or state when to choose this over alternatives.

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