TestWell Lab Tests

Reference range for a biomarker

lookup_reference_range

Read-onlyIdempotent

Physician-reviewed reference range for a blood test marker (130+ markers), filtered by sex and age when they matter, with what high and low values suggest, retest cadence, how to get tested, cited sources and the review date. Educational; the user's own report range takes precedence.

Input Schema

TableJSON Schema

Name	Required	Description
`age`	No
`sex`	No
`marker`	Yes	Marker name or alias, e.g. 'TSH', 'ferritin', 'HbA1c', 'LDL'
`pregnancy`	No
`postmenopausal`	No

Output Schema

TableJSON Schema

Name	Required	Description	Default
`found`	No
`units`	No
`browse`	No
`marker`	No
`ranges`	No
`retest`	No
`aliases`	No
`category`	No
`measures`	No
`citations`	No
`howToTest`	No
`lowSuggests`	No
`suggestions`	No
`highSuggests`	No
`filteredToQuery`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 6, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "additionalProperties": {},
+  "properties": {
+    "aliases": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "browse": {
+      "type": "string"
+    },
+    "category": {
+      "type": "string"
+    },
+    "citations": {
+      "items": {
+        "additionalProperties": {},
+        "properties": {
+          "label": {
+            "type": "string"
+          },
+          "url": {
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "filteredToQuery": {
+      "type": "boolean"
+    },
+    "found": {
+      "type": "boolean"
+    },
+    "highSuggests": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "howToTest": {
+      "items": {
+        "additionalProperties": {},
+        "properties": {
+          "kind": {
+            "type": "string"
+          },
+          "name": {
+            "type": "string"
+          },
+          "price": {
+            "description": "USD",
+            "type": "number"
+          },
+          "url": {
+            "description": "Absolute https URL on test-well.com",
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "lowSuggests": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "marker": {
+      "type": "string"
+    },
+    "measures": {
+      "type": "string"
+    },
+    "ranges": {
+      "items": {
+        "additionalProperties": {},
+        "properties": {
+          "max": {
+            "type": "number"
+          },
+          "min": {
+            "type": "number"
+          },
+          "qualifier": {
+            "description": "Who the band applies to, e.g. 'Female, age 18+'",
+            "type": "string"
+          },
+          "range": {
+            "type": "string"
+          },
+          "unit": {
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "retest": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "suggestions": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "units": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    }
+  },
+  "type": "object"
+}

First observedSep 6, 2026

TDQS

A4.1/5.0

Behavior5/5

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

Annotations already indicate read-only, idempotent, and non-destructive behavior, so the description adds substantial value by disclosing that ranges are physician-reviewed, filtered by sex/age when relevant, and enriched with interpretation guidance, retest cadence, sources, and review date. It also states the educational boundary and precedence rule, going well beyond the structured annotations.

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?

The description is a single, dense sentence that front-loads the core purpose and then lists the included content without repetition or filler. Every clause contributes useful information, making it easy for an agent to scan.

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?

Given the output schema exists, the description does not need to explain return values, and it covers the tool's content, filters, and educational precedence well. However, it omits guidance on the pregnancy and postmenopausal parameters and does not mention alternative sibling tools, leaving slight gaps for a fully self-sufficient description.

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 low (20%); only marker has schema documentation. The description adds meaning for sex and age filters, but it does not explain the pregnancy or postmenopausal boolean parameters, which are left undocumented in both the schema and description. This is a meaningful gap given that those parameters exist and their effect on reference ranges is not obvious.

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?

The description clearly states the tool looks up a physician-reviewed reference range for a blood test marker, covering 130+ markers and listing the key content delivered (high/low values, retest cadence, sources). It does not explicitly differentiate from sibling tools like search_tests or get_test, though the "reference range" focus makes the purpose reasonably distinct.

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 gives clear usage context: it is educational, and the user's own reported range takes precedence over the tool's output. It does not explicitly describe when to prefer this tool over its siblings, but the educational scope and precedence rule provide practical guidance for invocation.

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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