Finology MCP Server — deterministic federal student loan math for AI agents

Language models guess at federal student loan rules. This doesn't.

@finology/mcp-server connects Claude, Cursor, or any MCP client directly to Finology Software's parity-verified federal repayment engine. Every number is computed server-side against current federal rules and returned with a parityVerified flag. No formulas are approximated, and none are hardcoded into this package.

Why this exists

Federal repayment eligibility is not arithmetic, it is regulation, and it is the part models get wrong most confidently:

• A Parent PLUS loan is not RAP-eligible. Ask a model for the best plan on a Parent PLUS balance and it will usually produce a RAP payment. This server returns the exclusion and the rule behind it.
• RAP is assessed on full AGI with no poverty-line shield, on a sliding 1%–10% scale, less $50 per qualifying dependent — and a spouse is not a dependent. Approximating it from older IDR formulas gives the wrong answer.
• A consolidation that repaid a PLUS loan is restricted to ICR.
• PAYE and SAVE are closed to new enrollment.

Tools

compare_federal_student_loan_repayment_plans

Compares a balance across every plan the borrower is actually eligible for — RAP, IBR, ICR, PAYE, SAVE, Graduated, Extended, tiered Standard — returning monthly payment, lifetime cost, projected forgiveness and tax on forgiveness for each, plus the plans that are excluded and the eligibility rule that excludes them.

compare_married_filing_jointly_vs_separately_student_loans

For a married borrower, prices the filing-status decision. Filing separately removes the spouse's income from the income-driven payment calculation, which routinely moves the lifetime loan cost by tens of thousands of dollars.

It answers half the question on purpose, and says so. The engine models the loan side exactly and does not model the tax cost of filing separately — lost credits, worse brackets, community-property splits — which is often large enough to reverse the answer. Returning only the favourable half as if it were the whole decision would be the same confident half-truth this server exists to replace.

estimate_rap_monthly_payment

The RAP monthly payment alone, for the common case. Requires the borrower's AGI and refuses to proceed without it — an assumed zero returns the $10/month RAP floor, which reads exactly like a real answer.

Going further (no sales call, no marketing)

Every answer ends with the next rung, and finology_service_info returns it structured:

• Advisor: self-serve trial of Finology Software, no credit card.
• Developer / operator: an instant free sandbox key (POST https://api.finology.tech/v1/keys/sandbox, 100 calls/month), then the keyed endpoints with X-Api-Key. The keyed rung is the answer-of-record surface: every answer is persisted with its rule version and an inputs hash before it is served. Production limits by email until self-serve checkout ships. Docs: https://finology.tech/developers/

Install

Claude Desktop — add to claude_desktop_config.json:

{
  "mcpServers": {
    "finology": {
      "command": "npx",
      "args": ["-y", "@finology/mcp-server"]
    }
  }
}

No API key. No account. The calculation endpoints are public.

What is and is not in this repository

Not here, deliberately: the RAP/OBBB formulas, income-driven payment math, forgiveness and tax-bomb projection, plan-eligibility rules, and NSLDS parsing. Those run on Finology's servers.

That is not only about protecting the engine. Federal repayment rules move every year — poverty guidelines, tax brackets, RAP/OBBB implementation guidance, court challenges. A formula copied into an npm package is wrong within months and cannot be corrected in the installs that already exist. Calling a maintained endpoint is the only shape of this tool that stays true.

Here: the input schemas, the HTTP call, and error handling that passes the API's own field-level messages through to the model instead of flattening them into "request failed."

Limits

These tools return figures. They do not produce client-facing deliverables, save borrower records, parse NSLDS files, or track PSLF qualifying payments over time. For those, and for a book of borrowers kept current as the rules change: finology.tech

Rate-limited per IP. Not financial advice.

License

MIT