iso20022-mcp

explain_message

Explains an ISO 20022 payment message in plain language, clarifying who pays whom, how much, and status or reason details with deterministic, rule-based results.

Instructions

Plain-language summary of who pays whom, how much, and status/reasons. Deterministic, no guessing.

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": "explain_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

C2.7/5.0

Behavior2/5

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

No annotations, so the description carries the full burden. 'Deterministic, no guessing' usefully signals reproducible output, but it says nothing about whether malformed XML errors or degrades, whether the input must be a single transaction, or what the summary covers when status data is absent.

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

Conciseness4/5

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

Two short clauses, front-loaded with the output contents, with the determinism guarantee as a tight qualifier. Nothing wasted, though the space is used for output description rather than input/selection guidance.

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

Completeness3/5

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

An output schema exists, so return values needn't be described. But with no annotations, an undocumented required parameter, and a non-obvious verb among parse/validate siblings, the definition leaves the agent short of what it needs to call this confidently.

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 coverage is 0% for a single required parameter, and the description never explains what 'xml' should contain – a raw EDI/XML message string, a file path, or a parsed document. The implicit hint that a 'message' is being explained is the only added meaning.

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

Purpose3/5

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

It states what the output covers (who pays whom, amount, status/reasons) but never names the resource or input type, and the lone parameter is 'xml'. 'Explain' distinguishes it from parse/validate/generate siblings only vaguely – an agent can guess it's a narrative interpretation of a message, but the description doesn't say it takes an X12/EDI message or similar.

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

Usage Guidelines2/5

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

No when-to-use or when-not-to-use guidance, and no mention of parse_message or validate_message as alternatives. The only implicit signal is 'explain' vs the sibling verbs, which is inference, not 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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