Check or fill the check digit on a barcode number.
This tool declares no required parameters. Add optional parameters from the input schema as needed.
{
"id": 1,
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"arguments": {},
"name": "gtin_checksum"
}
}| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations and no output schema, so the description carries the full disclosure burden and does not meet it: it never says what is returned (a boolean verdict, a corrected number, an error), what happens on malformed or wrong-length input, or whether an existing valid check digit is preserved. The only behavioral hint is the check/fill duality in the verb choice.
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?
A single eight-word sentence with the resource front-loaded and no filler. Nothing can be trimmed without losing meaning.
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 tool with no annotations, no output schema, and an entirely untyped POST body, the description should at minimum state accepted barcode formats, the mode-selection mechanism, and the shape of the result. None of these are present, so an agent must guess before calling.
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 declares no properties (additionalProperties: true), so there are zero documented parameters to explain, which sets the baseline at 4. The description does add the one genuinely useful datum the schema omits: the payload is a barcode number whose check digit is the subject.
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?
Names a specific verb pair and resource: checking or filling the check digit on a barcode number. That is concrete enough for an agent to know exactly what computation happens, though it never names the GTIN's accepted lengths or which standards the digit follows.
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?
Usage is implied by the two named modes (check vs. fill), but the description never says how an agent selects between them, nor what happens with an already-valid number in fill mode. No alternatives or exclusions are offered, which is acceptable for a simple utility with no close siblings but leaves real ambiguity.
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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