Autoza UK

Check ULEZ / Clean Air Zone charges

check_clean_air_zone

Read-only

Check whether a car is compliant with UK clean air zones (London ULEZ, Bristol, Birmingham) and what it would cost to drive into them. Returns compliance, the daily charge per zone, and estimated annual cost. Only 3 of the 8 English charging zones charge private cars; Scotland uses Low Emission Zones, which issue penalties rather than a daily charge. Needs the registration year and fuel (the year is not needed for an electric car); a missing input returns an error naming it. Use for ULEZ, CAZ, clean air zone or emissions-charge questions.

Input Schema

TableJSON Schema

Name	Required	Description
`fuel`	Yes	Fuel type.
`days_per_year`	No	Days per year the driver would enter a charging zone, 0–366. Defaults to 250 (a daily commute).
`registration_year`	No	Year the car was first registered. Required unless fuel is "electric".

Output Schema

TableJSON Schema

Name	Required	Description
`_note`	Yes	Where the figures come from: Autoza, prices in GBP, distances in miles.
`compliant`	Yes
`exemption`	No	historic when an exemption decides the verdict, otherwise null.
`confidence`	Yes	certain, likely or borderline.
`explanation`	Yes
`scotland_note`	No
`official_checker`	Yes	The official registration checker to confirm against.
`annual_cost_basis`	No
`rates_verified_on`	Yes	When the charges were last checked against the official sources.
`estimated_annual_cost_gbp`	Yes
`oxford_zero_emission_zone`	No
`daily_charges_if_non_compliant`	Yes
`zones_that_charge_private_cars`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 6, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "_note": {
+      "description": "Where the figures come from: Autoza, prices in GBP, distances in miles.",
+      "type": "string"
+    },
+    "annual_cost_basis": {
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "compliant": {
+      "type": "boolean"
+    },
+    "confidence": {
+      "description": "certain, likely or borderline.",
+      "type": "string"
+    },
+    "daily_charges_if_non_compliant": {
+      "items": {
+        "properties": {
+          "charge_gbp_per_day": {
+            "type": "number"
+          },
+          "type": {
+            "type": "string"
+          },
+          "zone": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "zone",
+          "charge_gbp_per_day"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "estimated_annual_cost_gbp": {
+      "type": "number"
+    },
+    "exemption": {
+      "description": "historic when an exemption decides the verdict, otherwise null.",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "explanation": {
+      "type": "string"
+    },
+    "official_checker": {
+      "description": "The official registration checker to confirm against.",
+      "type": "string"
+    },
+    "oxford_zero_emission_zone": {
+      "properties": {
+        "charges_gbp_per_day": {
+          "items": {
+            "properties": {
+              "daily": {
+                "type": "number"
+              },
+              "vehicle": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "vehicle",
+              "daily"
+            ],
+            "type": "object"
+          },
+          "type": "array"
+        },
+        "hours": {
+          "type": "string"
+        },
+        "note": {
+          "type": "string"
+        },
+        "official": {
+          "type": "string"
+        }
+      },
+      "type": "object"
+    },
+    "rates_verified_on": {
+      "description": "When the charges were last checked against the official sources.",
+      "type": "string"
+    },
+    "scotland_note": {
+      "type": "string"
+    },
+    "zones_that_charge_private_cars": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "compliant",
+    "confidence",
+    "explanation",
+    "official_checker",
+    "daily_charges_if_non_compliant",
+    "estimated_annual_cost_gbp",
+    "zones_that_charge_private_cars",
+    "rates_verified_on",
+    "_note"
+  ],
+  "type": "object"
+}

Changed3 schema fields changedSep 23, 2026

changedInput schema / properties / days_per_year / description

Previous value: -"Days per year the driver would enter a charging zone. Defaults to 250 (a daily commute)."New value: +"Days per year the driver would enter a charging zone, 0–366. Defaults to 250 (a daily commute)."

changedInput schema / properties / registration_year / description

Previous value: -"Year the car was first registered."New value: +"Year the car was first registered. Required unless fuel is \"electric\"."

changedInput schema / required

Previous value: -[
-  "registration_year",
-  "fuel"
-]New value: +[
+  "fuel"
+]

First observedSep 1, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations already declare a safe read-only, closed-world operation, so the bar is lower. The description still adds real behavioral value: it names the returned fields, explains that a missing input returns an error naming the offending parameter, and states the year requirement is waived for electric cars.

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?

Front-loaded and dense with useful facts, with no filler sentences. The domain caveat about English vs Scottish zones is relevant but slightly interrupts the flow before the final usage sentence, keeping it just short of ideal.

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?

Covers inputs, the conditional-requirement edge case, error behavior, and the returned fields. With an output schema present, no further return-value documentation is needed, so the definition is complete for this tool's complexity.

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%, so the parameters are already documented, establishing a baseline of 3. The description's conditional note ('the year is not needed for an electric car') essentially restates what the schema already says via 'Required unless fuel is electric', adding little new semantic detail.

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 concrete verb and resource (check car compliance with UK clean air zones) plus the output it produces (compliance, daily charge per zone, estimated annual cost). The scope is narrow enough that an agent can distinguish it from siblings like calculate_car_tax or estimate_running_costs without reading the schema.

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?

Ends with an explicit trigger list ('Use for ULEZ, CAZ, clean air zone or emissions-charge questions'), which routes the agent well. It also clarifies domain boundaries (only 3 of 8 English zones charge private cars; Scotland's LEZs issue penalties not charges), though it never names a sibling tool to prefer or avoid.

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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