Medical Terminologies MCP

LOINC Answer Lists

loinc_answers

Read-onlyIdempotent

Retrieve valid answer lists for LOINC questionnaire items. Use to find standardized response options and validate data entry for survey questions.

Instructions

Get the list of valid answers for a LOINC questionnaire item.

Use this tool to:

Find valid response options for survey questions
Get answer codes for data entry validation
Look up standardized answer lists

Only applicable to LOINC codes that represent questions with defined answer sets.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`loinc_num`	Yes	LOINC number (e.g., "2339-0")

Output Schema

TableJSON Schema

Name	Required	Description
`answers`	Yes
`loinc_num`	Yes
`provenance`	Yes	Provenance block (contract v1.0): source, URL, data vintage, extraction instant, citation, license
`attribution`	Yes	Canonical source URLs of this response (attribution list)

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedv1.9.1Sep 1, 2026
- removedOutput schema / properties / provenance / properties / data_vintage / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / provenance / properties / data_vintage / type
```
Added value: +[
+  "string",
+  "null"
+]
```
- removedOutput schema / properties / provenance / properties / license / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / provenance / properties / license / type
```
Added value: +[
+  "string",
+  "null"
+]
```

Changed3 schema fields changedv1.8.0Aug 10, 2026

addedOutput schema / properties / attribution

Added value: +{
+  "description": "Canonical source URLs of this response (attribution list)",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / provenance

Added value: +{
+  "additionalProperties": false,
+  "description": "Provenance block (contract v1.0): source, URL, data vintage, extraction instant, citation, license",
+  "properties": {
+    "citation": {
+      "description": "Ready-to-use citation/attribution string",
+      "type": "string"
+    },
+    "data_vintage": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "Version/release of the data as exposed by the source; null when not exposed"
+    },
+    "license": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "License / legal regime of the data"
+    },
+    "retrieved_at": {
+      "description": "Real instant of the upstream extraction (ISO-8601, UTC). Responses served from cache keep the ORIGINAL fetch instant.",
+      "type": "string"
+    },
+    "source": {
+      "description": "Official upstream source of this data",
+      "type": "string"
+    },
+    "source_url": {
+      "description": "Canonical URL of the source (API base or dataset release)",
+      "type": "string"
+    }
+  },
+  "required": [
+    "source",
+    "source_url",
+    "data_vintage",
+    "retrieved_at",
+    "citation",
+    "license"
+  ],
+  "type": "object"
+}

changedOutput schema / required

Previous value: -[
-  "loinc_num",
-  "answers"
-]New value: +[
+  "loinc_num",
+  "answers",
+  "provenance",
+  "attribution"
+]

Changed3 schema fields changedv1.5.7Jun 21, 2026
- removedInput schema / additionalProperties
```
Removed value: -false
```
- addedOutput schema / properties / answers / items / properties / sequence / maximum
```
Added value: +9007199254740991
```
- addedOutput schema / properties / answers / items / properties / sequence / minimum
```
Added value: +-9007199254740991
```
First observedv1.2.1May 11, 2026

TDQS

A4/5.0

Behavior3/5

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds a meaningful scope constraint about LOINC codes with defined answer sets, but does not disclose behavior for non-applicable codes or the open-world nature of results hinted by openWorldHint. No contradiction with annotations.

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?

The description is front-loaded with the core purpose and then organized into helpful bullets. It is concise, though the three bullets overlap somewhat, and 'Look up standardized answer lists' adds little beyond the first two use cases.

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?

For a simple one-parameter lookup tool with rich annotations and an output schema, the description is sufficient. It states what the tool returns, when it applies, and typical use cases. No critical information needed to call it 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%, and the parameter already includes a pattern and example ('2339-0'). The description adds no extra parameter-level meaning beyond what the schema provides, so the baseline of 3 is appropriate.

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 action and resource: 'Get the list of valid answers for a LOINC questionnaire item.' It clearly differentiates from sibling LOINC tools like loinc_details, loinc_search, and loinc_panels by focusing specifically on answer sets for question items.

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?

Provides clear use cases via bullets: finding valid response options, answer codes for data entry validation, and standardized answer lists. It also adds an important scope constraint: 'Only applicable to LOINC codes that represent questions with defined answer sets.' It stops short of explicitly naming alternatives or stating when not to use it, so it misses the top score.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.