Free remote MCP server for deterministic validation of Australian Business Numbers (ABNs) and Australian Company Numbers (ACNs). Checks identifier format and checksum with no API key required.
Scored across 2 tools
The two tools target distinct identifiers — ABN for businesses and ACN for companies — so there is no ambiguity between them. The descriptions clearly differentiate scope and limitations.
Both tools follow the identical validate_<identifier> snake_case pattern, making the naming convention completely predictable and consistent.
Two tools is on the thin side, though the narrow purpose of validating two specific identifier types makes the count defensible. It feels slightly sparse compared to a typical well-scoped server.
The server covers the two primary Australian identifier validations with no obvious dead ends. Minor gaps exist, such as missing related identifiers or registration status checks, but the descriptions explicitly scope this out.
Validate the format and checksum of an Australian Business Number (ABN). This does not confirm that the ABN is registered or active.
| Name | Required | Description | Default |
|---|---|---|---|
| abn | Yes | Australian Business Number. Spaces and hyphens are accepted. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full behavioral burden and does disclose an important limitation: it does not confirm that the ABN is registered or active. This prevents the agent from over-trusting results. It does not describe return behavior or side effects, but the validation action is inherently read-only and the boundary statement is the most critical behavioral trait.
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 sentences with no wasted words: the first states the core action and target, the second adds a crucial caveat. Information is front-loaded and every sentence earns its place.
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 single-parameter validation tool with no output schema and no annotations, the description is nearly complete: it defines scope, accepted input behavior, and key limitations. It omits an explicit return-type description, but the tool name and purpose make a boolean/validation result strongly inferable, so this is a minor gap.
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 documents the abn parameter fully, including that spaces and hyphens are accepted. The description adds only the 'checksum' concept, which is behavior rather than parameter detail, so it does not meaningfully go beyond the schema-covered parameter semantics.
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 verb ('Validate') and precise resource ('format and checksum of an ABN'), making the tool's function immediately clear. It also distinguishes itself from the sibling validate_acn by targeting ABN rather than ACN, and explicitly clarifies what it does not do (confirm registration/active status).
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 usage context: use for syntactic/checksum validation of an ABN, not for legal or registration status verification. However, it never explicitly names when to use this tool over validate_acn or states selection criteria between the two siblings, so the guidance is only implicit.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Validate the format and checksum of an Australian Company Number (ACN). This does not confirm that the company is registered or active.
| Name | Required | Description | Default |
|---|---|---|---|
| acn | Yes | Australian Company Number. Spaces and hyphens are accepted. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden of behavioral disclosure. It discloses a key limitation (does not confirm registration), but does not describe the output format (e.g., boolean, error behavior) or edge cases. The behavior is partially transparent but not fully specified.
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 sentences, no fluff. The primary action is stated first, followed by a crucial limitation. All information is essential and front-loaded.
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 validation tool with no output schema, the description covers the essential purpose and a key limitation. It omits explicit return value behavior, but that is inferable from the verb 'validate'. The description is largely complete for calling the tool correctly.
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 schema description already covers the 'acn' parameter fully, including the fact that spaces and hyphens are accepted. The tool description adds no additional parameter semantics beyond what the schema provides. Baseline 3 is appropriate given 100% schema coverage.
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 verb 'validate' and the specific resource 'Australian Company Number', and specifies what is validated ('format and checksum'). It also explicitly distinguishes from registration confirmation, which differentiates it from a broader lookup tool and from the sibling validate_abn.
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 for format/checksum validation only, and the caveat 'This does not confirm that the company is registered or active' gives clear context that it should not be used for registration checks. However, it does not explicitly name alternatives or state when not to use it beyond that caveat.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
validate_abnvalidate_acn
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