validate_npwpValidate Indonesian NPWP format (15-digit legacy or 16-digit NIK format).
Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.
{
"id": 1,
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"arguments": {
"npwp": "<npwp>"
},
"name": "validate_npwp"
}
}| Name | Required | Description | Default |
|---|---|---|---|
| npwp | Yes |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's contribution is the scoping detail: this is a FORMAT check only, with two accepted shapes (15-digit legacy, 16-digit NIK). That is genuinely useful context beyond the structured fields. It stops short of saying what happens on failure or that it does not verify real registration status.
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 front-loaded sentence with the resource first and the format constraints in parentheses. No filler, no restating of the title, zero waste.
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, the description could state what a validation returns (boolean, or a parsed/derived structure) and what invalid input produces. For a one-parameter utility tool it is largely adequate, but the return shape is left entirely unstated.
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 0%, so the description carries the burden of explaining the single npwp parameter, and it does add the accepted digit lengths. However it omits whether punctuation is tolerated (e.g. dotted legacy form '12.345.678.9-012.000'), leaving a real ambiguity for the caller.
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?
Specific verb plus resource ("Validate Indonesian NPWP format") with the accepted variants named, so the agent knows exactly what is checked. It does not explicitly contrast with the adjacent validate_nik or generate_dummy_npwp tools, which keeps it from a 5.
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 only implied by the verb and resource; there is no explicit statement of when to reach for this versus validate_nik, nor that it should be used before storing a tax ID. No when-not or alternative routing is given, so the agent must infer intent from the name.
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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