Undertow MCP | Market liquidity and exit-cost tools

Endpoint: https://api.seiche.info/undertow/mcp (streamable HTTP, no install)

Try it live: liquilens-undertow.com/developers · API catalog: api.seiche.info/undertow

Undertow exposes estimated exit cost by position size and venue, the concentration of quoted depth, realized depth-collapse episodes, and liquidity tiers across market segments. This MCP 1.9.0 endpoint exposes 17 read-only tools, split into 9 public and 8 subscriber tools, plus 3 guided prompts. Its capability inventory is pinned to liquilens-undertow commit 1e68d93d27e2a6d572c1b17ccf50e36d1d2b869b, the hosted implementation at deploy/hetzner/undertow-mcp. The stdio discovery server in undertow_mm/mcp_server.py 1.8.0 is a different eight-tool surface and is not this registry listing.

Add it

Claude Code:

claude mcp add --transport http undertow https://api.seiche.info/undertow/mcp

Claude.ai / ChatGPT / Cursor: add a custom connector or MCP server with the URL above. No key and no wallet for the free surface.

This repository is the discovery and documentation mirror. The official registry serves io.github.beepboop2025/undertow version 1.9.0.

Related MCP server: polygon-mcp

Protocol compatibility

• 2026-07-28: stateless requests use server/discover, per-request _meta, MCP-Protocol-Version, and mirrored Mcp-Method / Mcp-Name routing headers.

• 2025-11-25, 2025-06-18, and 2025-03-26: retained legacy initialization, tools, prompts, notifications, batching, and ping behavior.

• Discovery identifies all nine public and eight subscriber tools. Anonymous tools/list returns only the public inventory; entitlement is checked fresh on every subscriber request.

• resources/list and resources/templates/list return explicit empty catalogs. resources/read returns a not-found error and never invents a resource.

Example

In the snapshot generated at 2026-08-08T15:01:22Z, selling $1,000,000 of BTC at the selected $1,000,000 published size rung cost 2.386 bp on Binance and 13.623 bp on Bitfinex: about $238.60 against $1,362.30. Gemini was the dearest observed venue in that same snapshot at 25.852 bp, or about $2,585.20.

Venue rankings can change during the day, and those differences are not visible in a single consolidated price. Undertow publishes the observation time and venue inputs with the estimate.

Tools

Prompts

Commodity futures are intentionally absent from that table. Undertow has no licensed point-in-time depth by contract month, venue and session, so executable commodity exit cost is CANNOT_ASSESS_EXECUTABLE_EXIT_COST; open interest or daily volume is never substituted. For aggregate WTI/Henry Hub cash pressure, Cushing and benchmark structure, call Seiche's public oil_funding_context or use /oil in @seiche_desk_bot.

Limitations

• PARTIAL is not calm. A segment reads PARTIAL when fewer than two of its measures have earned a scoring history. Four of nine segments read PARTIAL on 2026-07-30, and the board says so instead of guessing.

• Exit costs are estimates, interpolated from published quote depth at the 1% and 2% bands. Never a book walk. The snapshot refreshes roughly hourly, so it is a snapshot and not a real-time feed.

• Crypto measures are still accruing, so the board has not earned a crypto stress percentile and you should never quote one from it.

• The sealed record includes misses. Calls are hash-chained and signed before their outcomes are knowable, then scored against the point-in-time board.

• Commodity execution is a declared coverage gap. Ballast is useful upstream context from Seiche, not a depth ladder and not an Undertow exit-cost estimate.

Research and market data, not investment advice.

Subscriber tier

The Agent and Desk tiers unlock the eight subscriber tools. Send /agent to the Telegram bot to mint a bearer token:

{
  "mcpServers": {
    "undertow": {
      "url": "https://api.seiche.info/undertow/mcp",
      "headers": { "Authorization": "Bearer YOUR_TOKEN" }
    }
  }
}

The token proves identity only. Entitlement is re-read from live membership on every call, so access stops when the subscription does rather than when the token expires. Subscriber tools are invisible to an anonymous tools/list, and agent_access_status tells you where you stand.

Only tools/call is metered, reported on X-MCP-Usage-Used, X-MCP-Usage-Limit and X-MCP-Usage-Remaining. GET /undertow/mcp/usage is the self-meter. Hitting a quota returns a normal JSON-RPC result carrying isError and an upgrade pointer, never a dropped connection.

About this repository

This repo is the listing: a README and the two manifests that let directories describe the server accurately. The server itself is hosted at the endpoint above; its source is deploy/hetzner/undertow-mcp in the Undertow product repository and the registry target remains hosted 1.9.0. Nothing in this listing repo computes a number.

Verification and deployment boundary

Every push and pull request validates the exact 40-character releaseCommit in contract.json against the immutable source receipt in source-receipt.json. The receipt binds that commit and contract to SHA-256 digests of the hosted implementation and registry manifest without granting this public repository access to the private product repository. A maintainer creates or updates the receipt only after running the local pinned-core verifier against a clean checkout; that verifier derives the public/subscriber split, prompt inventory, protocol versions, server identity and registry manifest directly from the source and checks both artifact digests. A branch name or current product-repository HEAD is never accepted as release provenance.

A separate scheduled and manually dispatchable smoke makes anonymous, read-only calls to the listed endpoint. It initializes the legacy protocol, exercises modern discovery, checks the public tools, subscriber advertisement, prompts and explicit empty resource catalogs, then calls agent_access_status. It does not use a bearer token or exercise a subscriber tool. Run the same checks locally with:

python3 -m unittest discover -s tests -v
python3 scripts/verify_core_pin.py --receipt
python3 scripts/verify_core_pin.py --core /path/to/exact/core/checkout
python3 scripts/smoke_live_mcp.py

The source pin is a reviewed contract boundary, not an HTTP deployment receipt. Undertow's release controller records the deployed SHA and append-only receipts on the host, while the public MCP response currently reports its semantic version and capability catalog but no exact Git commit. Therefore a green live smoke proves the published behavior, not that the host runs this exact SHA. Do not repin this listing from a matching version or catalog alone; require the host's exact successful deployment receipt (or an equivalent authenticated SHA attestation) first.

Siblings from the same lab

• Seiche: US dollar funding stress.

• LiquiLens: bank, NBFC and lender failure risk, and whether that stress is reaching firms and households.

• groundcheck: claim grounding and citation verification for general text.

• Palimpsest: live internet-censorship signals.

Human front door: liquilens-undertow.com and the Telegram desk.