iso20022-mcp

validate_message

Validates pacs.008 and pacs.002 XML messages against ISO 20022 business rules, flagging format, amount, party, count, free-text, and injection issues with likely reject codes.

Instructions

Validate a pacs.008/pacs.002 message against business rules (IBAN checksum, BIC format, amounts, required parties, counts, free-text limits, prompt-injection patterns). Returns issues with likely reject codes.

Tool call template

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": {
      "xml": "<xml>"
    },
    "name": "validate_message"
  }
}

Input Schema

Name	Required	Description	Default
`xml`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 12, 2026

TDQS

A4/5.0

Behavior4/5

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

With no annotations, the description carries the burden and does disclose the substantive behavior: this is a non-mutating check, it enumerates exactly which validations run, and it states the return is a list of issues mapped to likely reject codes. Gaps: it doesn't say whether validation is fail-fast or returns all issues, and doesn't address size limits or behavior on unparseable input.

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?

Two sentences, both dense with information: the first front-loads the action, scope and rule set; the second front-loads the return contract. No filler or restatement of the tool name.

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

Completeness4/5

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

For a single-parameter validator with an output schema (so return shapes needn't be spelled out), this is nearly complete: scope, checks and output nature are all covered. It only falls short on input format assumptions and error/fail-fast behavior for malformed messages.

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 0% — the single 'xml' parameter has only a title, no description. The description partially compensates by identifying the expected payload as a pacs.008/pacs.002 message, but never confirms the format (raw XML string vs path), encoding expectations, or whether other message types are rejected.

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 (validate) plus the exact resource scope (pacs.008/pacs.002 messages) and enumerates the rule families checked: IBAN checksum, BIC format, amounts, required parties, counts, free-text limits, prompt-injection patterns. That enumeration makes it unambiguous against siblings like parse_message or explain_message, which operate on the same message type but do different things.

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

Usage Guidelines3/5

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

Usage is implied rather than stated: mentioning 'likely reject codes' suggests running this before submission, but the description never says when to call it versus explain_message or parse_message, nor any prerequisites (e.g. that the message must be well-formed XML). Adequate but leaves the routing decision to inference.

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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