Fes

⚠️ Experimental Project Notice

Community-Contributed Tool from Sisense Field Engineering

This project is an experimental tool developed by Sisense Field Engineering to facilitate customer learning and exploration of Sisense capabilities. It is not part of the core Sisense product release lifecycle and does not undergo the same validation, support, or certification processes as generally available (GA) Sisense features. It is provided "as-is" — see Support and contributing.

A standards-conformant MCP server that exposes Sisense environment operations as AI-ready tools, backed by the PySisense SDK: governance, asset and user/group management, lifecycle tasks, and well-checks — not chart-building or analytics Q&A.

It works for any Sisense user: every tool call runs with the calling user's own Sisense credential, so results and permissions are exactly what that user can see and do in Sisense itself, enforced natively by Sisense's APIs.

Tools only, no agent. Claude Desktop, Claude Code, claude.ai, Cursor — any MCP client brings its own agent; this project advertises and executes ~100 curated tools (dashboards, data models, users/groups, folders, plugins, health checks, …).

Architecture

The MCP spec's modern shape, as two cooperating services shipped as two Docker images (fes-auth, fes-mcp — built from one multi-stage Dockerfile with shared layers):

• fes-auth — the authorization server (AS). Owns everything about who is calling: OAuth 2.1 for MCP clients (PKCE, dynamic client registration, discovery), the browser sign-in page, and the credential vault mapping each issued MCP token to the user's Sisense token. It proxies every tool call to the resource server with the Sisense credential injected.
• fes-mcp — the resource server (RS). Stateless, OAuth-unaware. Reads the injected credential from each request, verifies it against Sisense (cached), and runs the tool as that user against that Sisense instance.

flowchart LR
    subgraph clients [MCP clients]
        C1[Claude Desktop]
        C2[Claude Code]
        C3[claude.ai / Cursor]
    end

    subgraph box [one host - docker compose]
        subgraph AS [fes-auth : authorization server]
            O[OAuth 2.1\nPKCE + DCR + discovery]
            L[/login page/]
            V[(vault\nMCP token → Sisense credential)]
            P[/mcp proxy\ninjects credential headers/]
        end
        subgraph RS [fes-mcp : resource server]
            T[Tool layer\nregistry-driven, ~100 tools]
            D[Dispatcher\nper-credential PySisense client]
        end
    end

    R[(tool registry JSON\nauto-generated from SDK)] -.defines.-> T

    C1 & C2 & C3 -- "MCP over HTTPS\nBearer <MCP token>" --> P
    C1 & C2 & C3 -. "browser: sign in once" .-> L
    P -- "Authorization: Bearer <Sisense token>\nX-Sisense-Url: <instance>\n(internal network only)" --> T
    T --> D
    D -- "REST, as the signed-in user" --> F[(Sisense Fusion Deployment)]

The seam between the two services is just those two headers plus the 401 contract, so each half can evolve — or be replaced — without the other noticing. There is deliberately no shared secret between the two — trust is the internal network (the RS's port is never published).

Sign-in flow (what a user experiences)

Each user adds the connector once in their MCP client, naming their own Sisense instance in the URL:

https://your-host/mcp?target=https://acme.sisense.com

sequenceDiagram
    participant U as User (browser)
    participant C as MCP client
    participant A as fes-auth
    participant S as Sisense

    C->>A: POST /mcp?target=<sisense url>  (no token)
    A-->>C: 401 + resource metadata URL (carries target)
    C->>A: discovery + client registration (RFC 7591)
    C->>U: open browser at A's /login
    Note over U,A: target present → instance fixed,<br/>only username/password asked<br/>(no target → domain field shown)
    U->>A: username/password (or API token for SSO)
    A->>S: POST /api/v1/authentication/login
    S-->>A: user's Sisense token (kept server-side, in the vault)
    A-->>C: authorization code → MCP access token (PKCE)
    Note over C,A: from here, silent — token refresh is automatic

The client never sees Sisense credentials; the server never stores passwords (used once to mint the user's token, then discarded). Users on SSO/MFA instances sign in by pasting their personal Sisense API token instead.

Tool call (steady state)

sequenceDiagram
    participant C as MCP client
    participant A as fes-auth (proxy)
    participant R as fes-mcp (tools)
    participant S as Sisense (target)

    C->>A: POST /mcp  (Bearer <MCP token>)
    A->>A: validate token → vault → Sisense credential
    A->>R: same request + Authorization: Bearer <Sisense token><br/>+ X-Sisense-Url: <instance>
    R->>S: verify credential (TTL-cached) · SDK call as that user
    S-->>R: result (user's permissions, user in audit log)
    R-->>A: MCP response (streamed)
    A-->>C: MCP response (streamed)

Credential lifecycle and self-healing

• The resource server re-verifies each (instance, token) pair against Sisense after FES_MCP_VERIFY_TTL seconds (default 300). A token revoked in Sisense turns into an HTTP 401 within at most that window.
• fes-auth treats an RS 401 as credential dead: it deletes the vault entry and re-challenges the MCP client, whose next move is to re-run the sign-in flow. Server-side revocation therefore propagates with no manual steps.
• Sessions are in-memory by design (no database): restarting fes-auth signs everyone out — each user's next call pops the browser login again (with ?target= set, that's just username/password). Restarting fes-mcp is invisible: it holds no state.

Deployment (docker compose)

docker compose up --build

This builds the two images (docker build --target fes-auth|fes-mcp) and publishes only fes-auth on :8200; fes-mcp stays internal. Terminate TLS in front (ALB / nginx / Caddy) — MCP clients require HTTPS for OAuth — and set FES_MCP_PUBLIC_URL to that public URL:

FES_MCP_PUBLIC_URL=https://your-host.example.com docker compose up -d --build

Users then add https://your-host.example.com/mcp?target=https://their-instance.sisense.com as a custom connector. The ?target= part is optional — without it the login page asks for the Sisense URL as a third field.

Endpoints on fes-auth: /mcp (proxied MCP), /login, /.well-known/* + /authorize + /token + /register (OAuth 2.1), / (status), /healthz. Hardening included: per-IP login rate limiting, CSRF-protected login form, access logs with request ids.

Quick start (local dev)

Requires Python 3.11+ and uv. Local dev skips the AS entirely: stdio transport defaults to env auth — one credential from .env, everything runs as you.

uv sync
cp .env.example .env   # set SISENSE_DOMAIN / SISENSE_TOKEN
uv run fes-mcp         # stdio transport

MCP client config (e.g. claude_desktop_config.json):

{
  "mcpServers": {
    "sisense": {
      "command": "uv",
      "args": ["run", "--directory", "/absolute/path/to/fes_mcp", "fes-mcp"]
    }
  }
}

To run the full split locally without Docker:

FES_MCP_TRANSPORT=http uv run fes-mcp &                 # RS on :8200 (upstream auth)
FES_MCP_PORT=8300 FES_MCP_RS_URL=http://127.0.0.1:8200 uv run fes-auth
# connector: http://127.0.0.1:8300/mcp?target=https://your.sisense.com

Layout

• src/fes_mcp/ — settings (env config) · registry (load/filter) · dispatcher (per-credential SDK dispatch) · upstream (RS credential verification) · auth (OAuth provider + login page) · authserver (fes-auth service + proxy) · middleware (access logs) · server (FastMCP assembly)
• config/tools.registry.with_examples.json — auto-generated tool registry. Never handwritten; regenerate with ./refresh_registry.sh when PySisense updates.
• config/allowlist.txt — the curated tool surface, one tool per line. Delete/comment a line to remove a tool. Tools not listed are never exposed, so registry refreshes can't silently widen the surface. (Migration tools are deliberately not listed — they need a dual-instance connection this server doesn't model.)
• Mutating tools are gated behind FES_MCP_ALLOW_MUTATIONS=true — see Security for the full mutation safeguards.

Technical and security considerations

Credential handling

The MCP client never sees Sisense credentials, and the server never stores passwords — a password is used once against Sisense's login API to mint the user's own token, then discarded. Sisense tokens live in fes-auth's in-memory vault, keyed to the MCP access token, and survive refresh rotation. In dev mode the single env credential (SISENSE_DOMAIN/SISENSE_TOKEN) stays on your machine. Nothing is persisted to disk: a fes-auth restart wipes the vault (everyone re-signs-in) — the deliberate trade for having no database and no encryption-at-rest surface.

Hardening on the hosted surface: per-IP login rate limiting, CSRF-protected login form, access logs with request ids, and per-call tool logs (tool / user domain / outcome / duration).

Authorization

Nothing custom: authorization is Sisense's job. Every tool call runs with the calling user's own Sisense token, so Sisense enforces their real permissions on every API call and permission errors surface to the client verbatim. This is also why the server is not admin-only — any Sisense user gets exactly their own scope.

Trust between the two services

fes-auth ↔ fes-mcp trust is network-level: no shared secret. The RS's port must never be reachable from outside the internal network (compose publishes only fes-auth). Defense in depth: FES_MCP_ALLOWED_SISENSE_ORIGINS pins which Sisense origins the RS will accept in X-Sisense-Url.

Mutations

Mutating tools are exposed only when FES_MCP_ALLOW_MUTATIONS=true, always carry destructiveHint, are blocked server-side as a second layer when disabled, and are written to a mutation audit log.

On top of that, mutating tools ask the human for approval before executing — via MCP elicitation, on clients that declare the capability (Claude Code, Cursor, VS Code). A proceed/abort dialog opens mid-call disclosing the exact arguments; abort or decline changes nothing. On clients without elicitation (Claude Desktop, claude.ai) the call proceeds normally and the client's own tool-approval flow plus the destructiveHint annotation are the safeguard, as for any MCP server.

Proceeding without the dialog is a deliberate decision (fail-open), not an oversight: elicitation is an optional client capability and can be auto-answered by a misbehaving client, so it is treated strictly as UX — the authorization boundary is always the user's own Sisense permissions.

Data flow to the LLM provider

This server has no summarization or data-redaction layer: every tool result — full rows, not {ok, count} metadata — is returned to the MCP client and lands in the model's context. That is by design and is what makes multi-step tool chaining work: the model can only reason over, filter, and feed one tool's output into the next call if it actually sees the data.

The consequence: whoever connects this server to an MCP client is accepting that Sisense data (dashboard contents, query results, user lists, …) flows to that client's LLM provider — e.g. Anthropic, for Claude — under their own terms with that provider. The server cannot enforce or scope this; it is a per-deployment acceptance to make consciously.

Recommended usage guidelines

• Start read-only: keep FES_MCP_ALLOW_MUTATIONS=false (the default) until you've built confidence in a non-production environment.
• Curate config/allowlist.txt down to the tools your deployment actually needs — fewer tools means less data exposure and a clearer approval story.
• Prefer non-production Sisense instances while exploring; the tools are only as safe as the signed-in user's permissions.
• Test destructive operations with an MCP client that supports elicitation (Claude Code, Cursor) so you see the confirmation dialogs.

Configuration

Variable	Default	Used by	Purpose
SISENSE_DOMAIN / SISENSE_TOKEN	—	fes-mcp	dev-mode (env) credential
SISENSE_SSL_VERIFY	true	both	verify TLS when calling Sisense
FES_MCP_AUTH	by transport: http ⇒ upstream, stdio ⇒ env	fes-mcp	credential source
FES_MCP_TRANSPORT	stdio	fes-mcp	stdio or http
FES_MCP_HOST / FES_MCP_PORT	127.0.0.1 / 8200	both	HTTP bind
FES_MCP_PUBLIC_URL	—	fes-auth	public base URL (OAuth discovery/redirects)
FES_MCP_RS_URL	—	fes-auth	the resource server to proxy tool calls to
FES_MCP_VERIFY_TTL	300	fes-mcp	seconds a verified (instance, token) pair is trusted
FES_MCP_ALLOWED_SISENSE_ORIGINS	— (accept any)	fes-mcp	exact-match allowlist for X-Sisense-Url
FES_MCP_TOOLS	config/allowlist.txt	fes-mcp	comma-separated tool_ids / modules override
FES_MCP_ALLOW_MUTATIONS	false	fes-mcp	expose mutating tools
FES_MCP_REGISTRY_PATH	bundled registry	fes-mcp	alternate registry JSON
FES_MCP_LOG_LEVEL	INFO	both	log verbosity (stderr only)

Tests

uv run python -m pytest

(python -m matters: it puts the repo root on sys.path, which the test modules' from tests.conftest import … imports rely on.)

49 tests, no network and no credentials needed (Sisense and the SDK are mocked): registry selection, dispatcher validation/errors, MCP round-trips, mutation confirmation (approve/abort/decline/no-capability), upstream credential verification (injected headers, 401 contract, origin allowlist, TTL revocation), and the complete AS+RS split — OAuth dance with and without ?target=, discovery metadata, proxied tool calls, refresh rotation, self-healing on Sisense-side revocation, plus the abuse paths (forged CSRF, brute-force rate limit, expired sessions).

Registry regeneration

./refresh_registry.sh   # rebuild config/ from the installed PySisense SDK

New SDK methods land in the registry but stay hidden until explicitly added to config/allowlist.txt.

Support and contributing

This is an experimental, community-contributed project maintained by Sisense Field Engineering and provided "as-is."

• Do not open a GSS ticket — this is not a GA Sisense feature.
• For usage questions or help getting started, contact your Customer Success Manager (CSM), who will route feedback to the Field Engineering team.
• Issues and contributions are welcome through the repository.

License

MIT