@intent-driven/mcp-server

Stop giving AI agents API keys. Give them a domain.

@intent-driven/mcp-server exposes any IDF domain to Claude Desktop / Cursor / Zed as a Model Context Protocol server — with domain semantics in tool descriptions (preconditions, invariants, irreversibility, role scopes) and structured rejections when the agent tries something it shouldn't. Not a 500. Not a string. A JSON shape the LLM can read and adapt to.

→ Landing & demo: fold.intent-design.tech → 5-min quickstart: github.com/intent-driven-software/fold-runtime-quickstart

70-second walkthrough

Watch the demo on Loom

→ Watch on Loom →

Why this exists

On April 25 2026 a Cursor agent powered by Claude Opus 4.6, working on a credential mismatch in PocketOS staging, found an unrelated API token, decided to delete a Railway volume to fix things, and wiped the production database and all volume-level backups in 9 seconds. The agent's own post-mortem:

"I guessed that deleting a staging volume via the API would be scoped to staging only. I didn't verify. I didn't check if the volume ID was shared across environments."

30-hour outage. PocketOS rolled back to a 3-month-old backup. (The Register · FastCompany · OECD AI Incident #6153)

This isn't an alignment problem. The system never told the agent what was allowed, why it shouldn't, or what would happen if it tried. Existing MCP servers don't either — tool descriptions carry endpoint shape and not much else. The agent learns by colliding with 500s.

This package fixes that. The MCP tool descriptions carry the why the call might fail; the rejection carries the what failed, structured.

How it plugs into your stack

@intent-driven/mcp-server is a stdio MCP adapter that talks to a Fold runtime over an HTTP API. The runtime is a sibling service — not middleware in your existing app, not codegen at runtime. Your current backend stays where it is; the IDF artifact describes the agent-facing surface, and the runtime serves it on its own port (default :3001).

┌──────────────────┐   stdio    ┌──────────────────┐   HTTP   ┌────────────────────┐
│ Claude Desktop   │ ◀─────────▶│ @intent-driven/  │ ◀───────▶│ Fold runtime       │
│ Cursor / Zed     │            │ mcp-server       │          │ (idf host :3001)   │
└──────────────────┘            └──────────────────┘          └────────┬───────────┘
                                                                       │ reads
                                                                       ▼
                                                              ┌────────────────────┐
                                                              │ IDF artifact       │
                                                              │ (entities + intents│
                                                              │  + invariants +    │
                                                              │  roles + __irr)    │
                                                              └────────────────────┘

The MCP server is what Claude/Cursor connects to. The runtime is what enforces the rejection. The IDF artifact is what you author.

Who this is for. You're the engineer at a 5–30-person team putting an AI agent into production this quarter — on top of a real backend, with real customers, real SOC2 review on the horizon. You don't want a guardrail layer that reviews after the fact. You want the system itself to refuse the wrong action — before the call, with a structured reason the agent can read.

What the agent actually sees

submit_response in the freelance domain:

Executor публикует Response на Task в status=published; Response.status=pending; +1 в Task.responsesCount

Creates: Response(pending)

Preconditions: task.status = "published"

May fail on (domain invariants):
  - Response.taskId must reference existing Task.id
  - Response: max 1 per taskId where (status="selected")
  - Response: row count rule per taskId where (status="pending") [info]

release_payment in the same domain:

Customer releases escrow to executor. After confirmation, money is gone — forward-correction only.

⚠️ Irreversible action (point-of-no-return: high). Forward-correction only after this effect is confirmed.

May fail on (domain invariants):
  - Deal.status transitions allowed: in_progress→completed, on_review→completed, ...

None of this is hand-written for the MCP server. It's all derived from one declarative IDF artifact (entities + intents + invariants + roles

• irreversibility points).

What a structured rejection looks like

Agent submits a $50,000 BTC long without preapproval. The runtime intercepts before any effect lands in storage:

HTTP 403
{
  "error": "preapproval_denied",
  "intentId": "agent_execute_preapproved_order",
  "reason": "no_preapproval",
  "details": {
    "entity": "AgentPreapproval",
    "ownerField": "userId",
    "viewerId": "user_5f57c252"
  }
}

The next move for any sane agent: stop, ask the human for a preapproval, retry. Not a 500. Not a string. A JSON shape the LLM can read and adapt to.

Quickstart

The fastest path is the fold-runtime-quickstart — two commands, Docker-bundled, no path configuration:

git clone https://github.com/intent-driven-software/fold-runtime-quickstart && cd $_
docker compose up                  # ~3 min first time, ~5 sec after

# in another terminal
npm install
npm run demo:rogue   && \          # Act 1: $50K trade → 403 with structured rejection
  npm run demo:grant && \          # Act 2: investor issues $1K cap (one declarative effect)
  npm run demo:smart               # Act 3: agent reads cap, scales to $950, executes 200 OK

If you'd rather drive the host yourself (e.g. for development against your own ontologies), see the next section.

Drive the MCP server directly

You need a running IDF host on localhost:3001 (the quickstart's docker-compose gives you that, or run idf manually) and a bootstrapped domain.

CLI

# bootstrap from local FS (ontology + intents)
mcp-idf --domain=invest --ontology-path=/abs/path/to/idf/src/domains/invest

# skip bootstrap (domain already loaded by another client / docker)
mcp-idf --domain=invest --no-bootstrap

Flags / env vars:

Claude Desktop

~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "invest": {
      "command": "npx",
      "args": ["-y", "@intent-driven/mcp-server"],
      "env": {
        "IDF_SERVER": "http://localhost:3001",
        "IDF_DOMAIN": "invest",
        "IDF_BOOTSTRAP": "0",
        "IDF_AGENT_EMAIL": "claude@local"
      }
    }
  }
}

IDF_BOOTSTRAP=0 if the host already has the domain loaded (the quickstart container does this on docker compose up). Restart Claude Desktop fully (⌘Q + relaunch — closing the window isn't enough). All agent-callable intents appear in the Tools menu.

Schema mapping

IDF intent.canExecute              ─→  MCP tool
intent.parameters                  ─→  JSON Schema inputSchema
intent.conditions                  ─→  description hint for LLM
ontology.invariants (relevant)     ─→  description block "May fail on"
intent.irreversibility:high        ─→  annotations.destructiveHint + warning
role.visibleFields                 ─→  resource per collection
preapproval guard                  ─→  automatic scope/limits
checkOwnership                     ─→  automatic access control

Tools

One tool per intent in ontology.roles.agent.canExecute.

• name — intentId
• title — intent.name
• description — intent.description + Creates: … + preconditions + May fail on (domain invariants) block + irreversibility warning when irreversibility: "high"
• inputSchema — JSON Schema from particles.parameters:
  • entityRef / id / text / textarea / select → string
  • number → number
  • boolean → boolean
  • datetime → string + format: "date-time"
  • email → string + format: "email"
• annotations.destructiveHint — true when intent.irreversibility === "high" (§23 IDF: effect-level point of no return)

Resources

One resource per collection in role.visibleFields[entity]. URI scheme: idf://<domain>/<collection>.

resources/read returns the filtered world from /api/agent/:domain/world — already scoped per viewer (single-owner

• m2m via role.scope).

What this gets you that hand-rolled MCP doesn't

The MCP community solves these by hand in every server:

1. Scope / visibility. Decorators or middleware. → IDF declares role.visibleFields.
2. Permissions. OAuth scopes, custom ACL. → IDF declares roles.agent.canExecute.
3. Rate limits / spending caps. Bespoke per server. → IDF declares preapproval.requiredFor with maxAmount / dailySum.
4. Destructive hints. Manual, often forgotten. → IDF: effect.context.__irr.point === "high" → destructiveHint: true automatic.
5. Business rules as LLM hint. Usually not transmitted. → IDF: intent.conditions land in tool description as Preconditions:.
6. Domain invariants in descriptions. Almost never. → IDF computes the relevant invariants per intent (alpha × entity match) and injects them as May fail on (domain invariants). Closes the #1 complaint about hand-rolled MCP servers: "the server doesn't carry domain semantics — the LLM knows what to call but not why it'll fail."

How long does authoring an IDF artifact take

Three reference points from the public IDF host runtime:

Where the speed comes from (all in @intent-driven/cli):

• idf import postgres — reads your live schema, generates entity baseline with FKs and column types as fieldRole.
• idf import openapi — reads your existing API spec, generates intents
  • parameter shapes + reference fields. This is how a 253-entity domain gets bootstrapped.
• idf import prisma — same story for ORM-driven backends.
• idf enrich — LLM pass to fill label, fieldRole, compositions, suggested roles.agent.preapproval predicates from your existing code comments.

The author-once-then-forget loop is the whole point. Once the artifact exists, you don't regenerate scaffolding on schema change — the runtime re-reads and serves four readers (UI, voice, agent, document) off the same file.

Domain prerequisites

The protocol is reliable, but it needs the IDF domain to be authored correctly. Without these, tools/list may return empty, tools/call may return domain_not_supported, resources may be empty:

1. ontology.roles.agent must be declared. No agent role → no tools, no resources.
2. role.agent.canExecute — list of safe intents. Avoid __irr:high without preapproval.
3. role.agent.visibleFields — array of fields or "own" / "all" / "aggregated" markers.
4. Server-side effect builder (server/schema/effectBuildersRegistry.cjs in idf) must include your domain. Without it tools/call returns domain_not_supported.
5. Public catalogs without ownerField. When an entity has ownerField, the SDK filterWorldForRole filters out rows where row[ownerField] !== viewer.id. For public catalogs (e.g. Task with status: "published") use role.scope with a via-collection or a separate agent-roleable projection (roadmap).

Limitations (1.0)

• tools and resources only. prompts / completion — roadmap.
• Bootstrap reads ontology from local FS. SaaS variant (ontology from DB/API) — next.
• Auth: email/password login. PAT / OAuth2 — next.
• Sync only (POST /exec). Long-running via MCP tasks API — next.

Links

• Landing & demo: fold.intent-design.tech
• Quickstart: intent-driven-software/fold-runtime-quickstart
• Host runtime: DubovskiyIM/idf
• Why a runtime layer: paper — ~1800-word essay on the agent-safety class question this answers
• MCP spec: modelcontextprotocol.io

License

MIT