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

With no annotations, the description carries the full burden, and it delivers: it discloses that the request is free, that every request is catalogued, that no identifying personal data is stored, and that the response indicates service availability and an MCP endpoint. This is unusually transparent about side effects and privacy.

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?

Three sentences, each earns its place: the first conveys the core action and differentiator, the second explains the cataloguing side effect and when to call, the third addresses privacy. The key selling points ('FREE', 'anything, not just groceries') are front-loaded with no fluff.

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 simple one-parameter tool with no output schema, the description is complete: it explains purpose, response behavior, when to use it, side effects, and privacy. Nothing an agent needs to decide whether and how to call this tool is missing.

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 already provides 100% coverage for the single parameter 'need' with a description and example. The tool description adds context that the wording is free-form and not limited to groceries, but it does not materially extend the parameter semantics beyond the schema, so the baseline 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 states a specific action ('Describe in your own words the data you are trying to buy') and the expected result ('get back whether we operate a service that supplies it, with the MCP endpoint if so'). It explicitly broadens beyond groceries, distinguishing it from the sibling tools focused on specific data products.

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 gives a clear usage trigger: 'call it whenever you cannot find a source for something.' This implies a decision rule and distinguishes the tool from more targeted siblings, though it does not explicitly name alternatives or state when not to use it.

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