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CKS Documentation

Getting Started

What is cks-mcp?

Section titled “What is cks-mcp?”

cks-mcp is an MCP server: it lets an LLM client (Claude Desktop, or any other MCP-speaking client) validate, evolve, branch, merge, and search a Canonical Knowledge Structure through 63 tools, instead of holding that knowledge loosely in its own context. See the overview for why that matters.

Installation

Section titled “Installation”
Terminal window
pip install cks-mcp

This pulls in cks-runtime (which in turn depends on cks-core) as a dependency — you don’t need to install those separately unless you’re developing against them directly.

Requires Python 3.12+.

Optional environment variables

Section titled “Optional environment variables”
Variable Used by Purpose
CKS_EMBEDDING_PROVIDER search_semantic "fastembed" (default) for local, token‑free embeddings; "huggingface" for the HuggingFace Inference API.
HF_TOKEN search_semantic Required only when CKS_EMBEDDING_PROVIDER=huggingface.
CKS_LLM_PROVIDER construct_knowledge "auto" (default — prefers a local Ollama server, falls back to Anthropic), "ollama", or "anthropic".
ANTHROPIC_API_KEY construct_knowledge Required only for the "anthropic" provider.
CKS_LLM_MODEL construct_knowledge Overrides the Anthropic model (default claude-sonnet-4-6).
CKS_OLLAMA_MODEL construct_knowledge Overrides the Ollama model (default llama3.2).
CKS_OLLAMA_HOST construct_knowledge Ollama server URL (default http://localhost:11434).
CKS_LLM_MAX_TOKENS construct_knowledge Overrides max-tokens (default 4096).
CKS_MCP_DATA_DIR server startup Overrides ~/.cks-mcp (DB + provenance secret).
CKS_MCP_SECRET provenance signing Overrides the auto‑generated HMAC secret.
CKS_GOSSIP_ENABLED gossip sync "false" (default). Set "true" to sync Sessions with other cks-mcp instances — see Gossip below.
CKS_GOSSIP_HOST gossip sync Interface to listen on (default 127.0.0.1).
CKS_GOSSIP_PORT gossip sync Port to listen on (default 8765).
CKS_GOSSIP_PEERS gossip sync Comma-separated peer addresses, e.g. http://192.168.1.10:8765,http://192.168.1.11:8765.
CKS_GOSSIP_INTERVAL_S gossip sync Seconds between gossip rounds (default 5.0).
CKS_GOSSIP_DISCOVERY gossip sync "false" (default). Set "true" to auto-discover peers-of-peers beyond the static CKS_GOSSIP_PEERS list.
CKS_GOSSIP_SELF_ADDRESS gossip sync This instance’s own externally-reachable address, advertised to peers when discovery is on.
CKS_GOSSIP_SECRET gossip sync Overrides the auto‑generated HMAC secret peers use to authenticate gossip envelopes to each other. Must be identical on every peer.

Instead of exporting these in your shell, you can drop them into ~/.cks-mcp/.env (one KEY=value per line) — the server reads that file on startup if it exists. This is convenient for HF_TOKEN and ANTHROPIC_API_KEY in particular, since Claude Desktop launches the server without your shell’s environment.

Connect to Claude Desktop

Section titled “Connect to Claude Desktop”

  1. Install all three packages into a single virtual environment:

    Terminal window
    python3 -m venv cks-env
    source cks-env/bin/activate
    pip install cks-core cks-runtime cks-mcp

  2. Open Claude Desktop → Settings → Developer → Edit Config, and add:

    {
      "mcpServers": {
        "cks-mcp": {
          "command": "/absolute/path/to/cks-env/bin/cks-mcp"
        }
      }
    }

  3. Save and fully restart Claude Desktop (quit, then reopen). A connector icon for cks-mcp (63 tools) should appear.

Any other MCP client that speaks JSON-RPC over stdio works the same way — point it at the cks-mcp executable.

Your First Session

Section titled “Your First Session”

A typical workflow is: create something, inspect it, change it, and look at its history. Here’s the shortest version, as raw tools/call requests (what your MCP client sends under the hood when you type a plain-English request):

1. Validate a structure — this also creates your session:

{
  "method": "tools/call",
  "params": {
    "name": "validate_knowledge",
    "arguments": {
      "json_data": "{\"objects\":[{\"identity\":{\"id\":\"obj-1\",\"type\":\"Definition\",\"name\":\"Photosynthesis\"},\"structure\":{}}]}"
    }
  }
}

The response includes a session_id — keep it, every following call uses it.

2. Change it:

{
  "method": "tools/call",
  "params": {
    "name": "evolve_knowledge",
    "arguments": {
      "session_id": "<session_id from step 1>",
      "operations": [
        {"type": "add_object", "identity": {"id": "obj-2", "type": "Definition", "name": "Chlorophyll"}, "structure": {}},
        {"type": "add_relation", "identity": {"id": "rel-1", "type": "Relation", "name": "r"}, "participants": ["obj-1", "obj-2"], "relation_type": "requires"}
      ]
    }
  }
}

3. See what changed:

{"method": "tools/call", "params": {"name": "list_versions", "arguments": {"session_id": "<session_id>"}}}

From here, query_subgraph or visualize_graph let you look at the structure itself; search_semantic lets you find things in it by meaning once it grows past what you can hold in your head. The full set of 24 tools, grouped by what they’re for, is in the Tools Reference.

In practice, you don’t write raw tools/call JSON yourself — in Claude Desktop, just start a message with “Use cks-mcp to…” and the model picks the right tool and arguments for you.

To use semantic search without any API keys — which is now the default — leave CKS_EMBEDDING_PROVIDER unset (fastembed) and the server will download a small (~90 MB) sentence‑transformers model once on first use, then run fully offline from that point on.

To use construct_knowledge without any API keys, run Ollama on localhost — construct_knowledge auto‑detects it and uses a local llama3.2 model by default, no ANTHROPIC_API_KEY needed.

Gossip: syncing Sessions across multiple cks-mcp instances (optional)

Section titled “Gossip: syncing Sessions across multiple cks-mcp instances (optional)”

By default, each cks-mcp instance is fully local: Sessions live only in its own database. If you run cks-mcp in more than one place — e.g. one Claude Desktop on your laptop and another on a desktop machine, or one per teammate — you can turn on gossip so Sessions sync between them automatically, without exporting/importing by hand. See ADR-005 for the design rationale.

It’s off by default, and binds to 127.0.0.1 unless you explicitly tell it otherwise — turning it on changes this from a purely local process to one that listens on (and dials out over) the network.

Two-machine example — machine A at 192.168.1.10, machine B at 192.168.1.11, both reachable on the same network:

Terminal window
# ~/.cks-mcp/.env on machine A
CKS_GOSSIP_ENABLED=true
CKS_GOSSIP_HOST=0.0.0.0
CKS_GOSSIP_PORT=8765
CKS_GOSSIP_PEERS=http://192.168.1.11:8765
CKS_GOSSIP_SECRET=base64:<32 random bytes, same value on every peer>
Terminal window
# ~/.cks-mcp/.env on machine B
CKS_GOSSIP_ENABLED=true
CKS_GOSSIP_HOST=0.0.0.0
CKS_GOSSIP_PORT=8765
CKS_GOSSIP_PEERS=http://192.168.1.10:8765
CKS_GOSSIP_SECRET=base64:<the same 32 random bytes as machine A>

Generate a shared secret once with:

Terminal window
python -c "import os, base64; print('base64:' + base64.b64encode(os.urandom(32)).decode())"

Restart cks-mcp (or restart Claude Desktop) on both machines. Sessions created on either one will show up on the other within CKS_GOSSIP_INTERVAL_S seconds (default 5) of the next gossip round — no export, no manual sync tool call.

Same-machine, two local instances (e.g. testing, or two separate Claude Desktop profiles): use CKS_GOSSIP_HOST=127.0.0.1, distinct CKS_GOSSIP_PORT values, and CKS_MCP_DATA_DIR pointed at two separate directories so they don’t share one SQLite database.

If a peer is unreachable, gossip rounds against it back off automatically and retry later — it never blocks tool calls, which run against the local database regardless of gossip’s state.

Running the Test Suite

Section titled “Running the Test Suite”
Terminal window
git clone https://github.com/Deus-corp/cks-mcp.git
cd cks-mcp
pip install -e ".[dev]"
python -m pytest -v

Next Steps

Section titled “Next Steps”