FreightUtils MCP Server

CBM Calculator

cbm_calculator

Read-onlyIdempotent

Calculate cubic metres (CBM) for a shipment from per-piece dimensions. CBM is the standard volume unit in international shipping: 1 CBM = 1m x 1m x 1m = 1,000 litres, and ocean freight prices per "freight tonne" (1 CBM or 1,000 kg, whichever is greater).

Behavior: deterministic — identical inputs always return identical figures; total volume = pieces x per-piece CBM (totals are computed from unrounded figures and rounded only for display), with conversions to cubic feet, cubic inches and litres (exact factors: 1 ft = 0.3048 m). Missing or non-positive dimensions error with a validation message naming the parameter. Rate-limited: a limit error carries reset_at, the UTC time the allowance resets.

Returns: cbm_per_piece, total_cbm, cubic_feet, litres, cubic_inches and pieces under result, plus confidence, _source and citation (the FreightUtils v1 response envelope). Field names as this package serves them (snake_case); the hosted /api/mcp endpoint serves the same fields in camelCase (e.g. total_cbm → totalCbm).

Related: chargeable_weight_calculator (air billing weight from the same dims), consignment_calculator (multi-line totals), unit_converter (single conversions), shipment_summary (full composite analysis).

Input Schema

Name	Required	Description
`pieces`	No	Number of identical pieces (default: 1)
`width_cm`	Yes	Width in centimetres
`height_cm`	Yes	Height in centimetres
`length_cm`	Yes	Length in centimetres

Output Schema

Name	Required	Description	Default
`ok`	Yes
`_meta`	No
`as_of`	No
`result`	Yes
`status`	No
`_source`	Yes
`edition`	No
`citation`	Yes
`validity`	No
`warnings`	No
`confidence`	Yes
`missing_inputs`	No
`blocking_errors`	No
`envelope_version`	Yes
`normalized_input`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedNov 6, 2026

addedOutput schema / properties / _meta / properties / upstream

Added value: +{
+  "additionalProperties": {},
+  "properties": {
+    "datasets": {
+      "additionalProperties": {
+        "additionalProperties": {},
+        "properties": {
+          "kind": {
+            "anyOf": [
+              {
+                "enum": [
+                  "watched",
+                  "checksum-only",
+                  "manual"
+                ],
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ]
+          },
+          "last_success": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "reason": {
+            "type": "string"
+          },
+          "stale": {
+            "type": "boolean"
+          },
+          "state": {
+            "enum": [
+              "in_step",
+              "changed_upstream",
+              "schema_drift",
+              "unreachable",
+              "window_missed",
+              "unknown"
+            ],
+            "type": "string"
+          },
+          "window_days": {
+            "type": [
+              "number",
+              "null"
+            ]
+          }
+        },
+        "required": [
+          "state",
+          "kind",
+          "last_success",
+          "window_days",
+          "stale"
+        ],
+        "type": "object"
+      },
+      "propertyNames": {
+        "type": "string"
+      },
+      "type": "object"
+    },
+    "stale": {
+      "type": "boolean"
+    },
+    "state": {
+      "enum": [
+        "in_step",
+        "changed_upstream",
+        "schema_drift",
+        "unreachable",
+        "window_missed",
+        "unknown"
+      ],
+      "type": "string"
+    },
+    "state_read_at": {
+      "type": [
+        "string",
+        "null"
+      ]
+    }
+  },
+  "required": [
+    "state",
+    "stale",
+    "state_read_at",
+    "datasets"
+  ],
+  "type": "object"
+}

Changed1 schema field changedNov 6, 2026

addedOutput schema / properties / _meta / properties / ids

Added value: +{
+  "additionalProperties": false,
+  "properties": {
+    "pattern": {
+      "type": "string"
+    },
+    "scheme": {
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    }
+  },
+  "required": [
+    "scheme",
+    "pattern"
+  ],
+  "type": "object"
+}

Changed2 schema fields changedNov 4, 2026
- removedOutput schema / properties / _meta / properties / receipt / properties / reason / const
```
Removed value: -"key_required"
```
- addedOutput schema / properties / _meta / properties / receipt / properties / reason / enum
```
Added value: +[
+  "key_required",
+  "quota"
+]
```

Changed1 schema field changedOct 30, 2026

addedOutput schema / properties / _meta / properties / receipt

Added value: +{
+  "additionalProperties": {},
+  "properties": {
+    "created_at": {
+      "type": "string"
+    },
+    "dataset_version": {
+      "additionalProperties": {
+        "type": "string"
+      },
+      "propertyNames": {
+        "type": "string"
+      },
+      "type": "object"
+    },
+    "engine_version": {
+      "type": "string"
+    },
+    "inputs": {},
+    "reason": {
+      "const": "key_required",
+      "type": "string"
+    },
+    "receipt_hash": {
+      "type": "string"
+    },
+    "result": {
+      "additionalProperties": {},
+      "propertyNames": {
+        "type": "string"
+      },
+      "type": "object"
+    },
+    "schema_version": {
+      "type": "string"
+    },
+    "stored": {
+      "const": false,
+      "type": "boolean"
+    },
+    "tool": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "stored",
+    "reason",
+    "schema_version",
+    "receipt_hash",
+    "created_at",
+    "tool",
+    "inputs",
+    "dataset_version",
+    "engine_version",
+    "result"
+  ],
+  "type": "object"
+}

Changed1 schema field changedOct 29, 2026
- addedOutput schema / properties / _meta / properties / edition_basis
```
Added value: +{
+  "type": "string"
+}
```

Changed1 schema field changedOct 29, 2026

addedOutput schema / properties / _meta

Added value: +{
+  "additionalProperties": {},
+  "properties": {
+    "check_id": {
+      "type": "string"
+    },
+    "receipt_url": {
+      "type": "string"
+    }
+  },
+  "type": "object"
+}

Changed5 schema fields changedOct 29, 2026

addedOutput schema / properties / as_of

Added value: +{
+  "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
+  "type": "string"
+}

addedOutput schema / properties / edition

Added value: +{
+  "anyOf": [
+    {
+      "additionalProperties": false,
+      "properties": {
+        "applies_from": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "may_apply_until": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "name": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "name",
+        "applies_from",
+        "may_apply_until"
+      ],
+      "type": "object"
+    },
+    {
+      "type": "null"
+    }
+  ]
+}

changedOutput schema / properties / envelope_version / enum

Previous value: -[
-  "1",
-  "1.1"
-]New value: +[
+  "1",
+  "1.1",
+  "1.2"
+]

addedOutput schema / properties / missing_inputs

Added value: +{
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / status

Added value: +{
+  "enum": [
+    "ok",
+    "partial",
+    "not_found",
+    "unsupported",
+    "ambiguous"
+  ],
+  "type": "string"
+}

Changed2 schema fields changedOct 28, 2026
- removedOutput schema / properties / validity / properties / effective_to / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / validity / properties / effective_to / type
```
Added value: +[
+  "string",
+  "null"
+]
```
Changed1 schema field changedOct 8, 2026
- addedInput schema / additionalProperties
```
Added value: +false
```
Changed5 schema fields changedAug 11, 2026
- addedOutput schema / properties / _source / properties / authority_current_edition
```
Added value: +{
+  "type": "string"
+}
```
- addedOutput schema / properties / _source / properties / checked_at
```
Added value: +{
+  "type": "string"
+}
```
- addedOutput schema / properties / _source / properties / dataset_edition
```
Added value: +{
+  "type": "string"
+}
```
- removedOutput schema / properties / envelope_version / const
```
Removed value: -"1"
```
- addedOutput schema / properties / envelope_version / enum
```
Added value: +[
+  "1",
+  "1.1"
+]
```

Changed1 schema field changedJul 9, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "_source": {
+      "additionalProperties": false,
+      "properties": {
+        "checked": {
+          "type": "string"
+        },
+        "name": {
+          "type": "string"
+        },
+        "provenance_status": {
+          "enum": [
+            "verified",
+            "pending-verification",
+            "computed",
+            "live"
+          ],
+          "type": "string"
+        },
+        "source_url": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "name",
+        "checked",
+        "provenance_status"
+      ],
+      "type": "object"
+    },
+    "blocking_errors": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "code": {
+            "type": "string"
+          },
+          "message": {
+            "type": "string"
+          },
+          "recovery": {
+            "additionalProperties": false,
+            "properties": {
+              "action": {
+                "type": "string"
+              },
+              "params": {
+                "additionalProperties": {},
+                "propertyNames": {
+                  "type": "string"
+                },
+                "type": "object"
+              },
+              "tool": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "action"
+            ],
+            "type": "object"
+          }
+        },
+        "required": [
+          "code",
+          "message",
+          "recovery"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "citation": {
+      "additionalProperties": false,
+      "properties": {
+        "qualifier": {
+          "type": "string"
+        },
+        "text": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "text"
+      ],
+      "type": "object"
+    },
+    "confidence": {
+      "additionalProperties": false,
+      "properties": {
+        "basis": {
+          "enum": [
+            "deterministic",
+            "provenance",
+            "match_quality",
+            "freshness"
+          ],
+          "type": "string"
+        },
+        "level": {
+          "enum": [
+            "high",
+            "medium",
+            "low"
+          ],
+          "type": "string"
+        },
+        "score": {
+          "maximum": 1,
+          "minimum": 0,
+          "type": "number"
+        }
+      },
+      "required": [
+        "level",
+        "basis"
+      ],
+      "type": "object"
+    },
+    "envelope_version": {
+      "const": "1",
+      "type": "string"
+    },
+    "normalized_input": {
+      "additionalProperties": {},
+      "propertyNames": {
+        "type": "string"
+      },
+      "type": "object"
+    },
+    "ok": {
+      "type": "boolean"
+    },
+    "result": {
+      "additionalProperties": {},
+      "propertyNames": {
+        "type": "string"
+      },
+      "type": "object"
+    },
+    "validity": {
+      "additionalProperties": false,
+      "properties": {
+        "as_of": {
+          "type": "string"
+        },
+        "effective_from": {
+          "type": "string"
+        },
+        "effective_to": {
+          "anyOf": [
+            {
+              "type": "string"
+            },
+            {
+              "type": "null"
+            }
+          ]
+        }
+      },
+      "required": [
+        "as_of"
+      ],
+      "type": "object"
+    },
+    "warnings": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "code": {
+            "type": "string"
+          },
+          "details": {
+            "additionalProperties": {},
+            "propertyNames": {
+              "type": "string"
+            },
+            "type": "object"
+          },
+          "message": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "code",
+          "message"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "envelope_version",
+    "ok",
+    "result",
+    "confidence",
+    "_source",
+    "citation"
+  ],
+  "type": "object"
+}

First observedApr 23, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Annotations already cover readOnly/idempotent/non-destructive/closed-world, yet the description adds material behavior beyond them: determinism, that totals are computed from unrounded figures and rounded only for display, that invalid dimensions produce a validation error naming the parameter, and that rate-limit errors carry reset_at in UTC. It also notes snake_case vs the hosted endpoint's camelCase, which is a real behavioral difference an agent must handle.

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 with purpose, then Behavior, Returns and Related — a predictable structure with no filler sentences. The Returns paragraph is the weakest part: with an output schema present, enumerating result fields is largely redundant, and the camelCase aside is useful but sits oddly in that block.

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 4-parameter deterministic calculator, the description covers inputs (per-piece dims, pieces), computation and rounding rules, error behavior, rate limits, and sibling alternatives, while an output schema exists to cover return values. Nothing an agent needs to call this correctly and interpret failures appears to be missing.

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?

Schema coverage is 100%, so the baseline is 3, but the description adds meaning beyond the field descriptions: dimensions are per-piece, pieces multiplies into the total ("total volume = pieces x per-piece CBM"), and rounding is deferred to display. It does not restate units per parameter, but the multiplication semantics and per-piece scoping are genuinely additive.

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?

Opens with a specific verb+resource: "Calculate cubic metres (CBM) for a shipment from per-piece dimensions." It defines what CBM is and scopes the input as per-piece dimensions, and the Related section names the closely related siblings (chargeable_weight_calculator, consignment_calculator, unit_converter, shipment_summary) with one-phrase differentiators, so an agent can separate this from ldm_calculator or consignment_calculator without opening schemas.

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 Related block gives clear routing context by describing what each alternative does ("air billing weight from the same dims", "multi-line totals", "single conversions"), which implies selection conditions. There are no explicit when-not or exclusion statements (e.g. "use ldm_calculator instead when you need load metres/freight-tonne by volume-to-deck"), so guidance is clear but not fully enumerated.

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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