Jithox

Check an IBAN

verify_iban

Read-only

Check an IBAN's structure and check digits for 70+ countries, offline. It never claims the account exists or who owns it. Free, no token.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`iban`	Yes	The account number to check, as written — spaces and dashes are fine, e.g. "BE68 5390 0754 7034".
`expectedCountry`	No	Optional ISO 3166-1 alpha-2 country of the party being paid.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`data`	Yes
`kind`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed5 schema fields changedSep 25, 2026

removedInput schema / $schema

Removed value: -"http://json-schema.org/draft-07/schema#"

changedInput schema / properties / expectedCountry / description

Previous value: -"Optional ISO 3166-1 alpha-2 country of the party being paid. When given, the answer reports whether the account is issued in that country — as an observation with both countries named, never as a fraud verdict."New value: +"Optional ISO 3166-1 alpha-2 country of the party being paid."

removedInput schema / properties / iban / maxLength
```
Removed value: -64
```
removedInput schema / properties / iban / minLength
```
Removed value: -1
```

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "data": {
+      "type": "object"
+    },
+    "kind": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "kind",
+    "data"
+  ],
+  "type": "object"
+}

First observedSep 23, 2026

TDQS

A4.5/5.0

Behavior5/5

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

Annotations cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), and the description adds substantial context beyond them: the check is performed offline, requires no token, is free, and explicitly does not assert account existence or ownership. That tells the agent exactly what kind of answer to expect and what it cannot rely on.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short sentences, front-loaded with the core action and scope, followed by the limitation and the cost/auth note. No filler, no repetition of the title.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With annotations covering safety and an output schema covering return values, the description only needs to add scope, environment (offline/no token), and result limits — all of which it does. Nothing an agent needs to call this correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so both parameters (iban format tolerance, optional expectedCountry) are already documented in the schema. The description adds no parameter-level detail beyond that, so the baseline of 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource (check an IBAN) plus the exact scope of the check: structure and check digits, 70+ countries, offline. This is unambiguous next to siblings like check_vat_list or lookup_peppol_participant, which operate on different identifiers.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description draws a clear boundary on what the result means ('never claims the account exists or who owns it'), which tells the agent when this tool's answer is sufficient and when it is not. It does not, however, name an alternative tool to use for ownership/account existence checks, so it stops short of full routing guidance.

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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