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

Beyond the read-only annotation, the description discloses that results are scoped to the caller's own purchase history, matched by case-insensitive substring on 'name_normalized', sorted newest first, and returned with specific fields. This gives the agent substantial behavioral context that annotations alone do not provide.

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 front-loaded with the user question and the core behavior, then provides matching semantics, ordering, return fields, and filter options in compact form. Every sentence contributes useful information without repetition.

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?

For a four-parameter read-only history tool with no output schema, the description covers scope, matching logic, ordering, returned fields, and optional date/limit filters. The remaining details, such as limit default and maximum, are documented in the schema.

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?

With 0% schema description coverage, the description carries the burden and explains that 'query' is a case-insensitive substring match against 'name_normalized' and that 'from'/'to' use YYYY-MM-DD. It says 'limit' is optional but does not explain its default or maximum, leaving a small gap.

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 specific verb and resource: it returns the caller's purchase history for line items matching a product query, and frames the purpose as comparing where the caller bought a product cheaper. This clearly distinguishes it from ERP product search or price-setting siblings.

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 opening question and the note that 'The agent compares merchants/prices from the result' make the intended use case explicit. It does not name exclusions or alternative tools, so it stops short of full when/when-not guidance.

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