iso20022-mcp

lookup_code

Retrieves ISO 20022 status reason, transaction status, and charge bearer code details so you can verify codes instead of guessing.

Instructions

Look up an ISO 20022 status reason, transaction status or charge bearer code. Use this instead of 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": {
      "code": "<code>"
    },
    "name": "lookup_code"
  }
}

Input Schema

Name	Required	Description	Default
`code`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 12, 2026

TDQS

A3.7/5.0

Behavior3/5

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

No annotations exist, so the description carries the full behavioral burden. It discloses the domain of codes covered, which is real context, and an output schema documents the return shape. It says nothing about unknown/invalid code handling, case sensitivity, or whether the lookup spans all three code sets at once.

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 short sentences with no filler: purpose first, usage hint second. Nothing is repeated from the title or schema, and nothing needs trimming.

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 lookup with an output schema, purpose and intent are adequately covered. The only meaningful gap is failure behavior for an unrecognized code, which an agent would want to know before calling.

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

Parameters4/5

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

The schema is a bare untyped 'code' string at 0% description coverage, and the description compensates by enumerating the three code families the value may come from. That is genuine added meaning beyond 'code: string', though it does not clarify whether the family must be disambiguated or inferred.

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

Purpose4/5

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

States a specific verb (look up) and a specific resource (ISO 20022 status reason, transaction status, or charge bearer code), plus the three code families in scope. It distinguishes itself from siblings like parse_message/validate_message by operating on a single code rather than a whole message, though it never names that contrast explicitly.

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?

'Use this instead of guessing' implies usage (resolving a code you don't recognize) but gives no explicit when-not-to-use, no prerequisites, and no named alternative for related tasks such as understanding the surrounding message. Guidance is implied rather than stated.

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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