SpreadBench NCSX-IS — MCP server

Official Model Context Protocol server for SpreadBench NCSX-IS, an issuance-spread benchmark for AI-infrastructure (Neocloud) bonds.

What NCSX-IS measures. For each constituent bond, the coupon minus the US Treasury yield of matching tenor on that bond's pricing date, weighted by face value. It is a point-in-time issuance spread — event-driven, no daily frequency, and not a traded CDS level or a rating. SpreadBench publishes no credit ratings and no investment advice.

Live data: https://spreadbench.com · Methodology + DOI: https://spreadbench.com/methodology.html · JSON API: https://spreadbench.com/api.html

Two ways to connect

1. Remote (streamable-http, nothing to install)

{
  "mcpServers": {
    "ncsx": {
      "type": "streamable-http",
      "url": "https://spreadbench.com/mcp"
    }
  }
}

Free, no API key, no signup.

2. Local (stdio, same tool set)

npm install -g github:BrianTian818/spreadbench-ncsx-mcp
# or, without npm registry:
npm install -g https://spreadbench.com/download/ncsx-mcp-0.3.0.tgz

{
  "mcpServers": {
    "ncsx": { "command": "ncsx-mcp" }
  }
}

Both transports share one tool definition file (tools.js), so they never drift apart.

Tools

Fourteen read-only tools, all keyless. Every tool declares readOnlyHint: true / destructiveHint: false, so clients do not prompt for write permission.

Tool	Returns
`ncsx_latest`	Start here for "what is the level". Latest NCSX-IS reading, secured / unsecured sub-indices, constituent and issuer counts, notional, as-of date, methodology version, DOI, `data_status`
`ncsx_index`	Structural, not a single number. Full index definition, sub-index notionals, coverage notes
`ncsx_constituents`	The whole universe, no filter. All 13 constituent bonds: issuer, ticker, coupon, maturity, size, seniority, pricing date, matched Treasury, issuance spread in bp
`ncsx_bond`	Filtered lookup for one issuer — matches issuer / ticker / note keyword and returns only matching bonds
`ncsx_curve`	The Treasury par-yield curve used on the pricing date (14 tenors, linear interpolation, no extrapolation) plus recent history
`ncsx_sector`	US high-yield / investment-grade OAS reference series for comparison
`ncsx_filings`	SEC filing radar for 9 AI-infrastructure issuers, last 45 days, noise forms filtered; pricing-chain forms (FWP / 424B* / S-3*) flagged `pricing_signal`
`ncsx_marks`	Second, independent layer: quarterly fair-value marks from SEC Form N-PORT filings, converted to spread
`ncsx_wall`	Maturity wall by year with secured / unsecured split; pass `year` to drill into one cohort
`ncsx_stories`	Citable data stories recomputed live, each with headline numbers, bilingual page and a 1200x630 share card
`ncsx_facts`	16 quotable numbers, each with `value`, `unit`, `as_of`, a human-readable `calc` and a `source`; filter by `id` or `q`
`ncsx_events`	History as an event replay. 13 pricing events in order, level after each, change in bp and per-bond pull attribution (`pull_bp`), so pulls sum to the event delta; filter by `since` or `ticker`
`ncsx_ruler`	Reverse pricing. Given a coupon and a tenor: interpolated Treasury (never extrapolated), issuance spread, rank among the 13, gap to the index level and to the same-structure tier, and the index level after adding the bond at a given size. Pass `issuer` to get that issuer's own bonds already in the index as a pricing history. Recomputed on every call — nothing is stored. Also returns a like-for-like comparable set (`peer_set`: median / notional-weighted / range / rank inside the set; `peer_window_years` defaults to ±1y, and when the window is empty it falls back to the nearest tenor band with the distance stated).
`ncsx_methodology`	Methodology version, DOI, license, data sources and their licensing status, full formula chain

Three names from the demo-era server — ncsx_levels, ncsx_attribution, ncsx_weekly — are not listed any more, but still answer if an old client calls them: they return a structured retirement notice rather than an error.

Read `data_status` before you quote anything

Every payload carries a data_status field. This is the single most important field in the schema:

`data_status`	Meaning
`real_issuance`	Observed public issuance data. Safe to quote; reproducible from SEC filings.
`retired_seed` / `seed`	A withdrawn demo series. Numbers were generated for layout testing. Never quote as market levels.

If a tool returns status: "retired", the endpoint was withdrawn — read the replacement field and move on. Nothing in this server will silently hand you demo numbers.

Example prompts

"What is the current NCSX-IS spread, and how does the unsecured cohort differ from the secured one?"
"Which CoreWeave bonds are in the index and what spread did each price at?"
"Compare NCSX-IS against the US high-yield OAS over the last 90 days."
"Which Treasury tenors does the index lean on most?"
"Is the NCSX-IS level consistent with the latest SEC N-PORT marks?"
"A $1.5bn 5-year note at 8.25% — where does that price relative to this market, and what would it do to NCSX-IS?"
"How did NCSX-IS get from 517.7bp to 432.3bp, and which issuer pulled it the most?"

Conventions

Identifier: constituents are identified by issuer + coupon + maturity. They do not carry CUSIPs — do not query by CUSIP.
Units: spreads in basis points over the Treasury at pricing. Notionals in USD millions.
Frequency: event-driven. There is no T+1 update and no daily change field.
Reproducibility: every number is derived from public filings (SEC EDGAR) and the US Treasury par-yield curve. The methodology page states the exact formula and the interpolation rule.

Notes on naming

Older versions of this server exposed Composite / HY / IG tiers and 90-day daily series. Those came from a demo dataset and were withdrawn on 2026-11-04 in favour of the issuance-spread methodology (v0.2.0-real). The three retired names listed above remain callable only so that old clients receive an explicit notice instead of an error; they are hidden from tools/list.

Directory listings

This server is listed in the official MCP Registry as com.spreadbench/ncsx, and is indexed by Glama (A tier) and brick.blue. glama.json in this repo claims the listing for its maintainer.

License

MIT. Data is published for research and citation; SpreadBench does not provide credit ratings or investment advice.

ncsx

Documentation