Skip to main content
Glama

Credit GPS — Canadian credit

Which card for this purchase

compare_cards_for_purchase
Read-onlyIdempotent

Use this when someone asks which card to put a purchase on. Returns two answers for the amount given: the card that reports the least utilization impact, the card that is cheapest to carry, and the trade-off when those differ, because the card the bureaus notice least is often not the card with the lowest rate. Calculates scenarios from supplied figures; does not make payments, change accounts, fetch external data, or retain tool inputs.

Input Schema

NameRequiredDescriptionDefault
cardsYesThe person's revolving credit accounts. Ask for limit, statement balance, and statement closing date per card — those three drive everything.
amountYesPurchase amount in CAD.
targetUtilizationNoTarget utilization as a decimal. Defaults to 0.29 — one point under the 30% band.

Output Schema

NameRequiredDescriptionDefault
amountYes
disclosureYes
noCardFitsYes
blendedBeforeYes
cheapestToCarryYes
optionsDisagreeYes
bestForReportingYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changed
    • changedOutput schema / properties / bestForReporting / anyOf
      Previous value: -[
      -  {
      -    "additionalProperties": false,
      -    "properties": {
      -      "aprBps": {
      -        "anyOf": [
      -          {
      -            "type": "number"
      -          },
      -          {
      -            "type": "null"
      -          }
      -        ]
      -      },
      -      "bandAfter": {
      -        "enum": [
      -          "good",
      -          "elevated",
      -          "high"
      -        ],
      -        "type": "string"
      -      },
      -      "blendedAfter": {
      -        "type": "number"
      -      },
      -      "crossesBandUp": {
      -        "type": "boolean"
      -      },
      -      "name": {
      -        "type": "string"
      -      },
      -      "remainingHeadroom": {
      -        "type": "number"
      -      },
      -      "utilizationAfter": {
      -        "type": "number"
      -      }
      -    },
      -    "required": [
      -      "name",
      -      "utilizationAfter",
      -      "bandAfter",
      -      "blendedAfter",
      -      "crossesBandUp",
      -      "remainingHeadroom",
      -      "aprBps"
      -    ],
      -    "type": "object"
      -  },
      -  {
      -    "type": "null"
      -  }
      -]New value: +[
      +  {
      +    "additionalProperties": false,
      +    "properties": {
      +      "aprBps": {
      +        "type": [
      +          "number",
      +          "null"
      +        ]
      +      },
      +      "bandAfter": {
      +        "enum": [
      +          "good",
      +          "elevated",
      +          "high"
      +        ],
      +        "type": "string"
      +      },
      +      "blendedAfter": {
      +        "type": "number"
      +      },
      +      "crossesBandUp": {
      +        "type": "boolean"
      +      },
      +      "name": {
      +        "type": "string"
      +      },
      +      "remainingHeadroom": {
      +        "type": "number"
      +      },
      +      "utilizationAfter": {
      +        "type": "number"
      +      }
      +    },
      +    "required": [
      +      "name",
      +      "utilizationAfter",
      +      "bandAfter",
      +      "blendedAfter",
      +      "crossesBandUp",
      +      "remainingHeadroom",
      +      "aprBps"
      +    ],
      +    "type": "object"
      +  },
      +  {
      +    "type": "null"
      +  }
      +]
    • changedOutput schema / properties / cheapestToCarry / anyOf
      Previous value: -[
      -  {
      -    "additionalProperties": false,
      -    "properties": {
      -      "aprBps": {
      -        "anyOf": [
      -          {
      -            "type": "number"
      -          },
      -          {
      -            "type": "null"
      -          }
      -        ]
      -      },
      -      "monthsAtMinimum": {
      -        "anyOf": [
      -          {
      -            "type": "number"
      -          },
      -          {
      -            "type": "null"
      -          }
      -        ]
      -      },
      -      "name": {
      -        "type": "string"
      -      },
      -      "neverShrinksAtMinimum": {
      -        "type": "boolean"
      -      },
      -      "totalInterestAtMinimum": {
      -        "anyOf": [
      -          {
      -            "type": "number"
      -          },
      -          {
      -            "type": "null"
      -          }
      -        ]
      -      }
      -    },
      -    "required": [
      -      "name",
      -      "aprBps",
      -      "monthsAtMinimum",
      -      "totalInterestAtMinimum",
      -      "neverShrinksAtMinimum"
      -    ],
      -    "type": "object"
      -  },
      -  {
      -    "type": "null"
      -  }
      -]New value: +[
      +  {
      +    "additionalProperties": false,
      +    "properties": {
      +      "aprBps": {
      +        "type": [
      +          "number",
      +          "null"
      +        ]
      +      },
      +      "monthsAtMinimum": {
      +        "type": [
      +          "number",
      +          "null"
      +        ]
      +      },
      +      "name": {
      +        "type": "string"
      +      },
      +      "neverShrinksAtMinimum": {
      +        "type": "boolean"
      +      },
      +      "totalInterestAtMinimum": {
      +        "type": [
      +          "number",
      +          "null"
      +        ]
      +      }
      +    },
      +    "required": [
      +      "name",
      +      "aprBps",
      +      "monthsAtMinimum",
      +      "totalInterestAtMinimum",
      +      "neverShrinksAtMinimum"
      +    ],
      +    "type": "object"
      +  },
      +  {
      +    "type": "null"
      +  }
      +]
  2. Added

TDQS

A4.3/5.0
Behavior4/5

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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, and the description reinforces this by stating it does not make payments, change accounts, fetch external data, or retain inputs. It also discloses the dual-answer output and trade-off logic, adding useful context beyond the safety 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?

Three sentences, front-loaded with the trigger and output summary, followed by behavioral constraints. Every sentence carries distinct information with no waste.

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?

The tool has an output schema and full parameter coverage, so the description does not need to restate them. It still provides the missing conceptual context: the two competing answers, why they diverge, and the read-only calculation boundary. Nothing material is left ambiguous for an agent to call it correctly.

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 schema already documents all parameter meaning in detail. The description only refers generically to 'the amount given' and 'supplied figures,' adding no parameter-specific guidance beyond the structured schema.

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?

The description states a specific verb and resource: 'which card to put a purchase on,' and names the two outputs it returns (least utilization impact vs. cheapest to carry) plus the trade-off. This clearly distinguishes it from sibling explainer and simulator tools.

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 a clear trigger: 'Use this when someone asks which card to put a purchase on.' It does not explicitly name when to prefer a sibling such as simulate_paydown, but the framing is a definitive routing signal for purchase-allocation questions.

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

Try in Browser

Glama MCP Gateway

Add one secure layer between your agents and this server.

Resources