Compare prices for the same product across Google Shopping, Amazon, and eBay. Returns best price, worst price, potential savings, and a ranked price list.
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | Results per source (1-5, default: 3) | |
| query | No | Product to compare prices for (required) | |
| country | No | Country code (default: DE) |
Changes observed during successful MCP inspections.
Input schema / additionalPropertiesAdded value: +falseInput schema / properties / limit / maximumAdded value: +5Input schema / properties / limit / minimumAdded value: +1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses the return values (best price, worst price, potential savings, ranked list), giving some transparency. However, it omits potential caveats such as data freshness, possible missing products across sources, or that this is a read-only operation. The description adds moderate value beyond the schema but does not fully disclose behavioral 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?
The description is a single, well-structured sentence that front-loads the main action ('Compare prices...') and then lists the return values. Every word contributes to understanding the tool, with no repetition or wasted language.
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 description effectively communicates the core purpose and return values, which is sufficient for a 3-parameter read-only tool with no output schema. It does not explain the exact structure of the ranked price list, but the high-level return enumeration covers the essential context. Given the tool's simplicity and schema coverage, the description is mostly 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?
Schema description coverage is 100%, so the schema already fully documents all three parameters (limit, query, country) with their meanings and defaults. The description does not add additional parameter semantics beyond what the schema provides, so the baseline score of 3 applies.
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 tool's purpose with a specific verb ('Compare') and resource ('prices for the same product across Google Shopping, Amazon, and eBay'). It distinguishes itself from siblings like 'competitor_pricing' or 'product_search' by naming the exact comparison sources and the nature of the output.
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 implies the tool is used for comparing prices across specific marketplaces, but it does not provide explicit when-to-use or when-not-to-use guidance, nor does it mention alternatives among sibling tools. There is no clear direction on choosing this over similar tools like 'competitor_pricing'.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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