Credit GPS — Canadian credit

What a payment does to reported utilization

simulate_paydown

Read-onlyIdempotent

Use this when someone asks what happens if they pay a particular amount, or wants to compare two amounts. Returns a what-if for a specific payment on a specific card before it closes: reported utilization before and after, per card and blended. No score change is predicted. It is a calculation only; no payment is made. Calculates scenarios from supplied figures; does not make payments, change accounts, fetch external data, or retain tool inputs.

Input Schema

TableJSON Schema

Name	Required	Description
`cards`	Yes	The person's revolving credit accounts. Ask for limit, statement balance, and statement closing date per card — those three drive everything.
`today`	No	Today's date in the person's local timezone, yyyy-mm-dd. Pass it — the server otherwise falls back to UTC, which is a day ahead for Canadian evenings.
`amount`	Yes	Payment amount in CAD, posting before that card's statement closes.
`cardName`	Yes	Which card the payment goes on. Partial names are matched.

Output Schema

TableJSON Schema

Name	Required	Description
`amount`	Yes
`cardName`	Yes
`forecast`	Yes	No validated score prediction is available.
`disclosure`	Yes
`assumptions`	Yes
`blendedAfter`	Yes
`blendedBefore`	Yes
`cardBandAfter`	Yes
`payBeforeDate`	Yes
`cardBandBefore`	Yes
`cardUtilizationAfter`	Yes
`cardUtilizationBefore`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedSep 7, 2026

removedOutput schema / properties / forecast / anyOf

Removed value: -[
-  {
-    "additionalProperties": false,
-    "properties": {
-      "confidencePct": {
-        "type": "number"
-      },
-      "high": {
-        "type": "number"
-      },
-      "isEstimate": {
-        "const": true,
-        "type": "boolean"
-      },
-      "low": {
-        "type": "number"
-      }
-    },
-    "required": [
-      "low",
-      "high",
-      "confidencePct",
-      "isEstimate"
-    ],
-    "type": "object"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / forecast / description

Added value: +"No validated score prediction is available."

addedOutput schema / properties / forecast / type
```
Added value: +"null"
```

First observedSep 1, 2026

TDQS

A4.1/5.0

Behavior5/5

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

Beyond the annotations (readOnly, idempotent, non-destructive), the description adds substantial transparency: 'It is a calculation only; no payment is made' and explicitly states it 'does not make payments, change accounts, fetch external data, or retain tool inputs.' This fully discloses the tool's side effects and non-effects.

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 description is appropriately sized but contains some redundancy, such as repeating the calculation nature in 'Returns a what-if' and 'Calculates scenarios'. It is still clear and well-organized, but could be trimmed slightly without losing information.

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 tool's moderate complexity and the presence of a separate output schema, the description covers all essential aspects: purpose, output scope, and limitations. It does not address edge cases like multiple cards or overpayment, but these are likely covered by the schema and are not critical for an agent deciding to invoke the tool.

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?

The input schema already provides extensive descriptions for all parameters (100% coverage), including nuanced warnings like the meaning of 0 for creditLimit and aprPercent. The main tool description adds no additional parameter semantics, so the baseline score for high schema coverage applies.

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 clearly states the specific trigger ('when someone asks what happens if they pay a particular amount, or wants to compare two amounts') and the precise output ('reported utilization before and after, per card and blended'). It also explicitly distinguishes what it does not do ('No score change is predicted'), making the tool's purpose unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides a clear positive use case but does not mention when to prefer an alternative tool or when not to use it. While it implies that it is only for calculation and not for actual payments, it lacks explicit comparison against sibling tools, leaving some ambiguity about boundary conditions.

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

All Credit GPS — Canadian credit tools Inspect

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