nhtsa-vehicle-safety-mcp-server

Nhtsa Decode Vin

nhtsa_decode_vin

Read-only

Decode Vehicle Identification Numbers to extract make, model, year, body type, engine, manufacturing details, and safety equipment: airbags, stability and braking systems, tire pressure monitoring, and the driver-assistance features VPIC records for the configuration, such as automatic emergency braking, lane keeping, blind spot warning, backup camera, and adaptive cruise control. Pass one VIN, or several as an array or in one string separated by spaces, semicolons, or commas. Partial VINs are accepted, with * for unknown positions; send each partial VIN as its own string or array entry. A call decodes up to 50 VINs; VINs past the first 50 come back in deferredVins to pass back as vin.

Input Schema

Name	Required	Description	Default
`vin`	Yes	One VIN or several. A VIN is up to 17 letters, digits, or * for an unknown position (e.g., "1HGCM82633A004352"). Separate several VINs in one string with spaces, semicolons, or commas, or list them in an array; a string naming several VINs takes only full 17-character VINs, so send a partial VIN alone. Append ,YYYY to give one VIN its own model year (e.g., "1HGCM82633A004352,2003"). A call decodes up to 50 VINs and takes at most 500; VINs past the first 50 come back in deferredVins.
`modelYear`	No	Model year, a whole number, for every VIN without its own ,YYYY. Helps resolve ambiguity for pre-1980 or partial VINs.

Output Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`notice`	No	Present when VINs past the first 50 were deferred to deferredVins, or when VINs decoded with VPIC warnings (errorCode != 0) — check errorCode/errorText per vehicle.
`vehicles`	No	Decoded vehicle information per VIN
`deferredVins`	No	VINs past the first 50, in the order sent, present when the call named more VINs than it decodes. Each carries its model year as VIN,YYYY when one applied; pass this list as vin to decode them.
`effectiveQuery`	No	Number of VINs named and the path taken (single or batch), with how many were decoded and deferred when VINs were deferred.

Schema Changelog

Changes observed during successful MCP inspections.

Changed24 schema fields changedNov 4, 2026

changedInput schema / properties / modelYear / description

Previous value: -"Model year, a whole number. Helps resolve ambiguity for pre-1980 or partial VINs."New value: +"Model year, a whole number, for every VIN without its own ,YYYY. Helps resolve ambiguity for pre-1980 or partial VINs."

changedInput schema / properties / vin / anyOf

Previous value: -[
-  {
-    "description": "A single VIN string (up to 17 characters, * for unknown positions)",
-    "type": "string"
-  },
-  {
-    "description": "An array of up to 50 VINs for batch decode",
-    "items": {
-      "type": "string"
-    },
-    "type": "array"
-  }
-]New value: +[
+  {
+    "description": "One VIN, or several separated by spaces, semicolons, or commas.",
+    "type": "string"
+  },
+  {
+    "description": "VINs, one per entry or several per entry as in a single string; at most 500 entries.",
+    "items": {
+      "type": "string"
+    },
+    "maxItems": 500,
+    "type": "array"
+  }
+]

changedInput schema / properties / vin / description

Previous value: -"A single 17-character VIN (e.g., \"1HGCM82633A004352\") or an array of up to 50 VINs for batch decode. Partial VINs accepted — use * for unknown positions."New value: +"One VIN or several. A VIN is up to 17 letters, digits, or * for an unknown position (e.g., \"1HGCM82633A004352\"). Separate several VINs in one string with spaces, semicolons, or commas, or list them in an array; a string naming several VINs takes only full 17-character VINs, so send a partial VIN alone. Append ,YYYY to give one VIN its own model year (e.g., \"1HGCM82633A004352,2003\"). A call decodes up to 50 VINs and takes at most 500; VINs past the first 50 come back in deferredVins."

addedOutput schema / properties / deferredVins

Added value: +{
+  "description": "VINs past the first 50, in the order sent, present when the call named more VINs than it decodes. Each carries its model year as VIN,YYYY when one applied; pass this list as vin to decode them.",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

changedOutput schema / properties / effectiveQuery / description

Previous value: -"Number of VINs decoded and the path taken (single or batch)."New value: +"Number of VINs named and the path taken (single or batch), with how many were decoded and deferred when VINs were deferred."

changedOutput schema / properties / error / properties / data / properties / reason / description

Previous value: -"Machine-readable failure mode. Declared by this tool: `empty_vin_list`: The VIN list is empty or contains a blank VIN. `batch_too_large`: VIN array exceeds the batch limit. Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `empty_vin_list`: The VIN list is empty, or an entry is blank or holds only separators. `invalid_vin`: A VIN holds a character other than a letter A-Z, a digit, or *, runs past 17 characters, or is a partial VIN in a string that names several VINs. `batch_too_large`: The input names more than 500 VINs, or more than 50 on a server set to reject an over-cap batch rather than defer the rest. Other values are possible when a failure originates below the handler."

changedOutput schema / properties / error / properties / data / properties / reason / examples

Previous value: -[
-  "empty_vin_list",
-  "batch_too_large"
-]New value: +[
+  "empty_vin_list",
+  "invalid_vin",
+  "batch_too_large"
+]

changedOutput schema / properties / notice / description

Previous value: -"Present when one or more VINs decoded with VPIC warnings (errorCode != 0) — check errorCode/errorText per vehicle."New value: +"Present when VINs past the first 50 were deferred to deferredVins, or when VINs decoded with VPIC warnings (errorCode != 0) — check errorCode/errorText per vehicle."

addedOutput schema / properties / vehicles / items / properties / adaptiveCruiseControl

Added value: +{
+  "description": "Adaptive Cruise Control (ACC): Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / airBagLocSeatCushion

Added value: +{
+  "description": "Seat Cushion Air Bag Locations: a seating position, from Driver Seat Only or Passenger Seat Only through 1st Row (Driver and Passenger) to All Rows. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / backupCamera

Added value: +{
+  "description": "Backup Camera: Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / blindSpotIntervention

Added value: +{
+  "description": "Blind Spot Intervention (BSI): Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / blindSpotWarning

Added value: +{
+  "description": "Blind Spot Warning (BSW): Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / crashImminentBraking

Added value: +{
+  "description": "Crash Imminent Braking (CIB): Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / dynamicBrakeSupport

Added value: +{
+  "description": "Dynamic Brake Support (DBS): Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / forwardCollisionWarning

Added value: +{
+  "description": "Forward Collision Warning (FCW): Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / laneCenteringAssistance

Added value: +{
+  "description": "Lane Centering Assistance: Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / laneDepartureWarning

Added value: +{
+  "description": "Lane Departure Warning (LDW): Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / laneKeepingAssistance

Added value: +{
+  "description": "Lane Keeping Assistance (LKA): Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / parkingAssist

Added value: +{
+  "description": "Parking Assist: Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / pedestrianAutomaticEmergencyBraking

Added value: +{
+  "description": "Pedestrian Automatic Emergency Braking (PAEB): Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / rearAutomaticEmergencyBraking

Added value: +{
+  "description": "Rear Automatic Emergency Braking: Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / rearCrossTrafficAlert

Added value: +{
+  "description": "Rear Cross Traffic Alert: Standard, Optional, or Not Available for this VIN's configuration. Optional means the configuration offers it; the VIN does not record whether this vehicle has it. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

addedOutput schema / properties / vehicles / items / properties / tpmsType

Added value: +{
+  "description": "Tire Pressure Monitoring System (TPMS) Type: Direct or Indirect. Omitted when VPIC leaves it blank.",
+  "type": "string"
+}

Changed1 schema field changedOct 18, 2026

changedOutput schema / properties / error / properties / data / properties / reason / description

Previous value: -"Machine-readable failure mode. Declared by this tool: `empty_vin_list`: No non-empty VIN strings supplied. `batch_too_large`: VIN array exceeds the batch limit. Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `empty_vin_list`: The VIN list is empty or contains a blank VIN. `batch_too_large`: VIN array exceeds the batch limit. Other values are possible when a failure originates below the handler."

Changed6 schema fields changedAug 21, 2026

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "vehicles",
+      "effectiveQuery"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `empty_vin_list`: No non-empty VIN strings supplied. `batch_too_large`: VIN array exceeds the batch limit. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "empty_vin_list",
+            "batch_too_large"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "vehicles",
-  "effectiveQuery"
-]

Changed4 schema fields changedJul 30, 2026

changedInput schema / properties / modelYear / description

Previous value: -"Helps resolve ambiguity for pre-1980 VINs or partial VINs."New value: +"Model year, a whole number. Helps resolve ambiguity for pre-1980 or partial VINs."

addedInput schema / properties / modelYear / maximum
```
Added value: +9007199254740991
```
addedInput schema / properties / modelYear / minimum
```
Added value: +-9007199254740991
```
changedInput schema / properties / modelYear / type
```
Previous value: -"number"New value: +"integer"
```

Changed3 schema fields changedMay 30, 2026

addedOutput schema / properties / effectiveQuery

Added value: +{
+  "description": "Number of VINs decoded and the path taken (single or batch).",
+  "type": "string"
+}

addedOutput schema / properties / notice

Added value: +{
+  "description": "Present when one or more VINs decoded with VPIC warnings (errorCode != 0) — check errorCode/errorText per vehicle.",
+  "type": "string"
+}

changedOutput schema / required

Previous value: -[
-  "vehicles"
-]New value: +[
+  "vehicles",
+  "effectiveQuery"
+]

Changed3 schema fields changedApr 24, 2026

changedInput schema / properties / vin / anyOf

Previous value: -[
-  {
-    "type": "string"
-  },
-  {
-    "items": {
-      "type": "string"
-    },
-    "type": "array"
-  }
-]New value: +[
+  {
+    "description": "A single VIN string (up to 17 characters, * for unknown positions)",
+    "type": "string"
+  },
+  {
+    "description": "An array of up to 50 VINs for batch decode",
+    "items": {
+      "type": "string"
+    },
+    "type": "array"
+  }
+]

addedOutput schema / properties / vehicles / items / description
```
Added value: +"Decoded details for a single VIN"
```

changedOutput schema / properties / vehicles / items / properties / vin / description

Previous value: -"The decoded VIN"New value: +"The decoded VIN, echoed back from the request"

Changed5 schema fields changedApr 15, 2026

changedOutput schema / properties / vehicles / items / properties / errorText / description
```
Previous value: -"VPIC error/warning text"New value: +"VPIC error or warning text"
```

changedOutput schema / properties / vehicles / items / properties / make / description

Previous value: -"Vehicle manufacturer"New value: +"Vehicle manufacturer when provided by VPIC"

changedOutput schema / properties / vehicles / items / properties / model / description
```
Previous value: -"Vehicle model"New value: +"Vehicle model when provided by VPIC"
```
changedOutput schema / properties / vehicles / items / properties / modelYear / description
```
Previous value: -"Model year"New value: +"Model year when provided by VPIC"
```

changedOutput schema / properties / vehicles / items / required

Previous value: -[
-  "vin",
-  "make",
-  "model",
-  "modelYear",
-  "bodyClass",
-  "vehicleType",
-  "driveType",
-  "engineCylinders",
-  "engineDisplacementL",
-  "engineHP",
-  "fuelType",
-  "trim",
-  "manufacturer",
-  "plantCity",
-  "plantState",
-  "plantCountry",
-  "airBagLocFront",
-  "airBagLocSide",
-  "airBagLocCurtain",
-  "airBagLocKnee",
-  "electronicStabilityControl",
-  "abs",
-  "tractionControl",
-  "errorCode",
-  "errorText"
-]New value: +[
+  "vin"
+]

First observedApr 13, 2026

TDQS

A3.9/5.0

Behavior4/5

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

Beyond readOnlyHint=true, the description discloses non-obvious behavior: a 50-VIN soft cap, that overflow returns in deferredVins to be re-submitted, and the 500-entry array limit. These are real operational constraints an agent would otherwise discover only by trial. It does not discuss error behavior for malformed VINs, keeping it short of a 5.

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 capability statement is front-loaded and the batching limits follow logically. The middle sentence on separators and partial VINs duplicates the schema almost verbatim, which is redundant but not confusing, so the text stays readable despite mild padding.

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?

With an output schema present, the description need not explain return values, and it still flags the one output field (deferredVins) that changes caller behavior. Batch limits, partial-VIN handling, and the modelYear override are all covered, leaving only cross-tool routing unaddressed.

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 100% and the schema already documents the string/array union, delimiters, the ',YYYY' year suffix, and the modelYear fallback. The description largely restates those mechanics; its only added semantic is the deferredVins round-trip, so the baseline 3 applies.

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 leads with a specific verb and resource ('Decode Vehicle Identification Numbers') and enumerates the returned data categories (make, model, year, engine, safety equipment), which is far more informative than the title alone. It does not explicitly contrast itself with siblings like nhtsa_lookup_vehicles, so sibling differentiation is only implicit through the VIN-specific framing.

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?

It gives clear operational guidance: one VIN or a batch, delimiters for multi-VIN strings, partial VINs with '*', and the rule that a partial VIN cannot be embedded in a multi-VIN string. What is missing is any when-to-use routing versus the sibling lookup/safety tools, so it describes how to call rather than when to choose it.

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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