Get a full free Data Finder plan for up to three sources: fit, cost at your monthly volume, resale terms with recorded clause, URL and read date, and build-it-yourself guidance. No live source lookup. Defaults: volume 0, US, no resale. (API Tool Calls, by Cowerx)
| Name | Required | Description | Default |
|---|---|---|---|
| geo | No | ||
| resell | No | ||
| volume | No | ||
| use_case | Yes | Describe the data you need and what you want to build. |
Changes observed during successful MCP inspections.
Input schema / properties / geoAdded value: +{
+ "maxLength": 200,
+ "minLength": 1,
+ "type": "string"
+}Input schema / properties / resellAdded value: +{
+ "enum": [
+ "yes",
+ "no"
+ ],
+ "type": "string"
+}Input schema / properties / volumeAdded value: +{
+ "maximum": 1000000000000000,
+ "minimum": 0,
+ "type": "integer"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, and it does disclose non-obvious behavior: no live lookup is performed, the plan is free, it is capped at three sources, and defaults are volume 0 / US / no resale. It omits any mention of authentication, rate limits, latency or how deterministic the 'plan' is, which matters for a no-annotation tool.
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?
Two dense sentences, front-loaded with the deliverable and then the constraints and defaults. 'full free' is mild marketing padding, but nothing is structurally wasteful.
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?
With no output schema and no annotations, the description usefully enumerates what the returned plan contains (fit, cost, resale terms with clause, URL and read date, DIY guidance), which stands in for an output schema. It remains thin on parameter formats and on any auth or operational constraints for a 4-param tool.
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 coverage is only 25% (just use_case), so the description must compensate. It partially does by supplying defaults for volume, geo and resell, which the schema does not state, but it adds no guidance on valid geo values, sensible volume ranges, or what a good use_case string looks like.
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?
States a concrete verb and deliverable: it produces a 'Data Finder plan' covering fit, cost, resale terms, URL/read date and DIY guidance. The scope ('up to three sources') and the 'No live source lookup' limit make the output distinguishable, though the term 'Data Finder plan' is somewhat branded and undefined. Siblings (barcode, transcript, seo_check, etc.) are unrelated, so no sibling routing is required.
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 an implied trigger (you need a data-sourcing plan) and one useful exclusion, 'No live source lookup', plus stated defaults for volume, geo and resale. It never states when to prefer this over another approach or what preconditions must hold, so usage is inferred rather than explicit.
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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