# 🧠 MCP Knowledge Graph Architecture Manifest (Final)

## 0. Purpose

Define a **strict, minimal, and general architecture** for MCP systems that operate on knowledge graphs.

This architecture separates:

* graph execution
* semantic intelligence (enrichment)
* domain-specific operations

It is **deliberately rigid** to ensure:

* clarity for agents
* composability of systems
* long-term scalability

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# 1. Core Principles

### 1.1 Absolute Separation

Each layer has one responsibility:

* execution
* intelligence
* application

These MUST NOT overlap.

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### 1.2 Enrichment is Abstract

Enrichment is NOT:

* geography-specific
* ontology-specific
* domain-specific

Enrichment IS:

> **the discovery of related entities under defined constraints**

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### 1.3 Ontologies are Data

* Ontologies are inputs
* Ontologies are not hardcoded logic
* Ontologies can vary per system

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### 1.4 Everything is a Graph

* entities
* relations
* ontologies
* queries

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# 2. System Architecture

```text
[ Domain-Specific MCPs ]
            ↓
        [ Atlas MCP ]
            ↓
     [ Virtuoso MCP ]
```

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# 3. Layer Definitions

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## 3.1 Virtuoso MCP

(Virtuoso MCP)

### Role

> **Graph execution layer**

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### Responsibilities

* store RDF triples
* execute SPARQL queries
* provide graph primitives

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### Capabilities

* traversal by predicate
* node description
* relation enumeration
* path queries
* prefix handling (technical)
* named graph management

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### MUST NOT

* interpret meaning
* resolve entities
* enrich data
* depend on external sources

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### Philosophy

> “Executes graph operations without understanding them.”

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## 3.2 Atlas MCP

### Role

> **Semantic intelligence layer**

Atlas is the **only layer allowed to interpret and enrich data**.

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# 4. Enrichment (Formal Definition)

Enrichment is defined as:

> **The controlled expansion of an entity into a set of related entities based on structural, semantic, or constraint-based relationships.**

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## 4.1 Enrichment Dimensions

Atlas MUST support enrichment along arbitrary axes:

### Structural

* hierarchy (parent, child)
* adjacency
* graph distance

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### Semantic

* type similarity
  (e.g. “musicians”)

* shared attributes
  (e.g. “born 1965”)

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### Constraint-based

* filtered relations
* query-defined sets

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## 4.2 Examples (All Equivalent Forms of Enrichment)

* “Find parent regions of Kumasi”
* “Find musicians born in 1965 in Ghana”
* “Find entities with same profession as X”
* “Find all siblings in a pedigree graph”
* “Find all servers connected via health routes”

👉 These are NOT different features
👉 They are **instances of the same abstraction**

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## 4.3 Core Enrichment Operation

```text
expand(entity, constraints, depth) → subgraph
```

Where:

* `entity` = starting node
* `constraints` = predicates, types, filters
* `depth` = traversal boundary

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## 4.4 Key Rule

> Atlas provides the mechanism of enrichment
> Domain-specific MCPs define what is relevant

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# 5. Ontology Handling

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## 5.1 Ontology Layers

Atlas operates on three ontology types:

### External Ontologies

* Wikidata
* other knowledge graphs

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### Canonical Ontology (REQUIRED)

Atlas MUST define a **minimal internal schema**

Purpose:

* normalize external data
* provide stable structure

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### Domain Ontologies

Defined by domain-specific MCPs:

* facts-mcp
* garden-mcp
* news-mcp
* etc.

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## 5.2 Core Rule

> Atlas translates between ontologies but owns none of them

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## 5.3 Ontology Mapping

Atlas MUST:

* ingest ontologies
* map external → canonical
* optionally map canonical → domain

Atlas MUST NOT:

* assume domain semantics
* enforce domain schemas

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# 6. Atlas Responsibilities

### 6.1 Entity Resolution

* text → entity identifiers

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### 6.2 Graph Acquisition

* retrieve data from:

  * external knowledge graphs
  * internal graph store

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### 6.3 Ontology Mediation

* align different schemas
* normalize representations

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### 6.4 Enrichment Execution

* perform expansion queries
* apply constraints
* return structured subgraphs

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### 6.5 Persistence

* store results via Virtuoso MCP

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### 6.6 Data Layers (MANDATORY)

Atlas MUST maintain:

#### Raw Layer

* source-aligned data
* full provenance

#### Canonical Layer

* normalized structure

#### Derived Layer

* enrichment results
* computed relations

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### Philosophy

> “Atlas turns graphs into usable knowledge.”

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## 3.3 Domain-Specific MCPs

### Definition

> A **domain-specific MCP** is any MCP that:

* serves a specific purpose
* defines its own ontology
* uses Atlas and/or Virtuoso to operate on graph data

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### Examples

* Facts MCP
* Garden MCP
* News MCP

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### Role

> **Application and decision layer**

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### Responsibilities

* define domain ontology
* define relevance and constraints
* invoke Atlas for enrichment
* store/query via Virtuoso MCP

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### Capabilities

* tagging
* classification
* domain-specific inference
* state representation

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### MUST NOT

* resolve entities independently
* perform enrichment logic outside Atlas
* duplicate ontology mapping logic

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### Key Rule

> Domain-specific MCPs define *what to ask*
> Atlas defines *how to answer*

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# 7. Facts MCP (Clarified)

### Role

> **Domain-specific MCP for authoritative state**

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### Responsibilities

* define “current truth” in its domain
* maintain state using its ontology
* query enriched data via Atlas

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### Example

```text
:ServerA :isOperational true
```

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### Key Rule

> “Fact” is a domain concept, not a system concept

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# 8. Prefix Handling

| Layer                | Responsibility                     |
| -------------------- | ---------------------------------- |
| Virtuoso MCP         | technical prefix resolution        |
| Atlas MCP            | namespace interpretation & mapping |
| Domain-Specific MCPs | domain-specific prefixes           |

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# 9. Data Flow

```text
Input (text / entity / query)
        ↓
Domain-Specific MCP
        ↓
Atlas MCP
    - resolve
    - enrich
    - map ontologies
        ↓
Virtuoso MCP
    - execute
    - persist
        ↓
Domain-Specific MCP
    - apply domain logic
```

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# 10. Hard Rules

### Rule 1

Virtuoso MCP MUST remain purely operational

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### Rule 2

Atlas MCP is the ONLY semantic intelligence layer

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### Rule 3

All enrichment MUST go through Atlas

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### Rule 4

All ontology mapping MUST go through Atlas

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### Rule 5

Domain-specific MCPs MUST NOT duplicate enrichment logic

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### Rule 6

Domain-specific MCPs define relevance, not mechanisms

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# 11. Final Model

```text
Virtuoso MCP  → executes graph operations
Atlas MCP     → performs semantic expansion
Domain-Specific MCPs → define purpose and meaning
```

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# 12. Final Statement

> Build systems where:
>
> * the graph layer executes
> * the semantic layer expands
> * the domain-specific layer decides
>
> and no layer crosses its boundary.

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