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tessera-mcp-server
The MCP server that returns money, not data.
Status: v0.1.3 — published 2026-05-27 on npm with sigstore SLSA provenance v1, listed on registry.modelcontextprotocol.io.
Tessera is an LLM proxy that optimizes API spend through multi-provider routing, prompt compression, audit-immutable logging, output-length prediction, and batch arbitrage. This package exposes Tessera as an MCP server for tool-using agents — Claude Desktop, Claude Code, Cursor, Cline, Continue, Goose, Zed.
Where other LLM-infrastructure MCP servers return logs, traces, or prompt metadata, this one returns savings decisions: what's drifting, what to switch, what to approve, what to audit.
See it in action
▶ 41-second walkthrough: live counter ticks · baseline $74,800 → actual $30,000 ($44,800 saved, 60% reduction) · audit-immutable savings ledger. Click to play.
Install
npx @tessera-llm/mcp-serverOr add to your client config:
Claude Desktop (~/Library/Application Support/Claude/claude_desktop_config.json on macOS, %APPDATA%\Claude\claude_desktop_config.json on Windows):
{
"mcpServers": {
"tessera": {
"command": "npx",
"args": ["-y", "@tessera-llm/mcp-server"],
"env": {
"TESSERA_API_KEY": "tk_..."
}
}
}
}Claude Code (.mcp.json in project root):
{
"mcpServers": {
"tessera": {
"command": "npx",
"args": ["-y", "@tessera-llm/mcp-server"],
"env": {
"TESSERA_API_KEY": "tk_..."
}
}
}
}Cursor (~/.cursor/mcp.json):
{
"mcpServers": {
"tessera": {
"command": "npx",
"args": ["-y", "@tessera-llm/mcp-server"],
"env": { "TESSERA_API_KEY": "tk_..." }
}
}
}Get a TESSERA_API_KEY at tesseraai.io/dev — Free Sandbox is 60M tokens/month with no card.
Tools
v0.1 exposes 6 tools (5 read + 1 mutate). Hard cap — no tool sprawl.
| Tool | Read/Write | Purpose |
|---|---|---|
tessera_list_workloads | read | List your mapped workloads with anchor cost + current m-stack. |
tessera_get_savings_report | read | Anchored spend + measured savings for a window. |
tessera_get_recommendation_queue | read | Pending Optimize-tab recommendations with expected lift + confidence. |
tessera_get_ledger_entries | read | Audit-immutable Monthly Reading rows (provider call, mechanic stack applied, savings). |
tessera_get_quality_snapshot | read | SLA floor + p50/p95 quality scores + drift events. |
tessera_approve_recommendation | mutate | Move a queued mechanic from "suggested" to "active" with audit-trail entry. |
Provider config writes, API-key management, composition cap changes, and Stripe operations are deliberately NOT in this surface — they live in the dashboard, where blast-radius requires explicit modal confirmation.
Transport
- stdio (default) — local clients (Claude Desktop, Cursor, Cline, Continue, Claude Code)
- Streamable HTTP (optional) — set
TESSERA_MCP_TRANSPORT=httpto bind onlocalhost:8788for remote / Goose / Zed-via-mcp-remote
SSE (deprecated in MCP spec 2025-11-25) is not supported.
Auth
TESSERA_API_KEY env var or Authorization: Bearer <key> header (HTTP transport). Same API key as the SDK — tk_* format. Future v0.2: OAuth 2.1 (aligned with MCP spec RC 2026-07-28).
Security posture
- Tools receiving user-controlled content (ledger notes, recommendation rationale strings, workload names) are labelled
__untrusted__to prevent prompt-injection cascade per the Supabase/Cursor 2025 pattern. mcp-scan(Invariant Labs) runs in CI to catch tool-poisoning attacks in tool descriptions.- No
execute_codeescape hatch. Typed verbs only. - No session-based auth. Every request authenticates independently per MCP spec 2026 requirement.
License
Apache-2.0. Tessera is a product of Fintechagency OÜ (Estonia, Tallinn).
Links
- Tessera landing: tesseraai.io
- Free Sandbox signup: tesseraai.io/dev
- How it works: tesseraai.io/how-it-works
- MCP protocol spec: modelcontextprotocol.io