#!/usr/bin/env node
/*MIT License
Copyright (c) 2025 Anthropic, PBC
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
import { Server } from "@modelcontextprotocol/sdk/server/index.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import {
CallToolRequestSchema,
ListToolsRequestSchema,
} from "@modelcontextprotocol/sdk/types.js";
import { promises as fs } from 'fs';
import path from 'path';
import { fileURLToPath } from 'url';
// Define memory file path using environment variable with fallback
export const defaultMemoryPath = path.join(path.dirname(fileURLToPath(import.meta.url)), 'memory.jsonl');
// Handle backward compatibility: migrate memory.json to memory.jsonl if needed
export async function ensureMemoryFilePath(): Promise<string> {
if (process.env.MEMORY_FILE_PATH) {
// Custom path provided, use it as-is (with absolute path resolution)
return path.isAbsolute(process.env.MEMORY_FILE_PATH)
? process.env.MEMORY_FILE_PATH
: path.join(path.dirname(fileURLToPath(import.meta.url)), process.env.MEMORY_FILE_PATH);
}
// No custom path set, check for backward compatibility migration
const oldMemoryPath = path.join(path.dirname(fileURLToPath(import.meta.url)), 'memory.json');
const newMemoryPath = defaultMemoryPath;
try {
// Check if old file exists and new file doesn't
await fs.access(oldMemoryPath);
try {
await fs.access(newMemoryPath);
// Both files exist, use new one (no migration needed)
return newMemoryPath;
} catch {
// Old file exists, new file doesn't - migrate
await fs.rename(oldMemoryPath, newMemoryPath);
return newMemoryPath;
}
} catch {
// Old file doesn't exist, use new path
return newMemoryPath;
}
}
// Initialize memory file path (will be set during startup)
let MEMORY_FILE_PATH: string;
// We are storing our memory using entities, relations, and observations in a graph structure
export interface Entity {
name: string;
entityType: string;
observations: string[];
}
export interface Relation {
from: string;
to: string;
relationType: string;
}
export interface KnowledgeGraph {
entities: Entity[];
relations: Relation[];
}
// The KnowledgeGraphManager class contains all operations to interact with the knowledge graph
export class KnowledgeGraphManager {
constructor(private memoryFilePath: string) {}
private async loadGraph(): Promise<KnowledgeGraph> {
try {
const data = await fs.readFile(this.memoryFilePath, "utf-8");
const lines = data.split("\n").filter(line => line.trim() !== "");
return lines.reduce((graph: KnowledgeGraph, line) => {
const item = JSON.parse(line);
if (item.type === "entity") graph.entities.push(item as Entity);
if (item.type === "relation") graph.relations.push(item as Relation);
return graph;
}, { entities: [], relations: [] });
} catch (error) {
if (error instanceof Error && 'code' in error && (error as any).code === "ENOENT") {
return { entities: [], relations: [] };
}
throw error;
}
}
private async saveGraph(graph: KnowledgeGraph): Promise<void> {
const lines = [
...graph.entities.map(e => JSON.stringify({
type: "entity",
name: e.name,
entityType: e.entityType,
observations: e.observations
})),
...graph.relations.map(r => JSON.stringify({
type: "relation",
from: r.from,
to: r.to,
relationType: r.relationType
})),
];
await fs.writeFile(this.memoryFilePath, lines.join("\n"));
}
async createEntities(entities: Entity[]): Promise<Entity[]> {
const graph = await this.loadGraph();
const newEntities = entities.filter(e => !graph.entities.some(existingEntity => existingEntity.name === e.name));
graph.entities.push(...newEntities);
await this.saveGraph(graph);
return newEntities;
}
async createRelations(relations: Relation[]): Promise<Relation[]> {
const graph = await this.loadGraph();
const newRelations = relations.filter(r => !graph.relations.some(existingRelation =>
existingRelation.from === r.from &&
existingRelation.to === r.to &&
existingRelation.relationType === r.relationType
));
graph.relations.push(...newRelations);
await this.saveGraph(graph);
return newRelations;
}
async addObservations(observations: { entityName: string; contents: string[] }[]): Promise<{ entityName: string; addedObservations: string[] }[]> {
const graph = await this.loadGraph();
const results = observations.map(o => {
const entity = graph.entities.find(e => e.name === o.entityName);
if (!entity) {
throw new Error(`Entity with name ${o.entityName} not found`);
}
const newObservations = o.contents.filter(content => !entity.observations.includes(content));
entity.observations.push(...newObservations);
return { entityName: o.entityName, addedObservations: newObservations };
});
await this.saveGraph(graph);
return results;
}
async deleteEntities(entityNames: string[]): Promise<void> {
const graph = await this.loadGraph();
graph.entities = graph.entities.filter(e => !entityNames.includes(e.name));
graph.relations = graph.relations.filter(r => !entityNames.includes(r.from) && !entityNames.includes(r.to));
await this.saveGraph(graph);
}
async deleteObservations(deletions: { entityName: string; observations: string[] }[]): Promise<void> {
const graph = await this.loadGraph();
deletions.forEach(d => {
const entity = graph.entities.find(e => e.name === d.entityName);
if (entity) {
entity.observations = entity.observations.filter(o => !d.observations.includes(o));
}
});
await this.saveGraph(graph);
}
async deleteRelations(relations: Relation[]): Promise<void> {
const graph = await this.loadGraph();
graph.relations = graph.relations.filter(r => !relations.some(delRelation =>
r.from === delRelation.from &&
r.to === delRelation.to &&
r.relationType === delRelation.relationType
));
await this.saveGraph(graph);
}
async readGraph(): Promise<KnowledgeGraph> {
return this.loadGraph();
}
// Very basic search function
async searchNodes(query: string): Promise<KnowledgeGraph> {
const graph = await this.loadGraph();
// Filter entities
const filteredEntities = graph.entities.filter(e =>
e.name.toLowerCase().includes(query.toLowerCase()) ||
e.entityType.toLowerCase().includes(query.toLowerCase()) ||
e.observations.some(o => o.toLowerCase().includes(query.toLowerCase()))
);
// Create a Set of filtered entity names for quick lookup
const filteredEntityNames = new Set(filteredEntities.map(e => e.name));
// Filter relations to only include those between filtered entities
const filteredRelations = graph.relations.filter(r =>
filteredEntityNames.has(r.from) && filteredEntityNames.has(r.to)
);
const filteredGraph: KnowledgeGraph = {
entities: filteredEntities,
relations: filteredRelations,
};
return filteredGraph;
}
async openNodes(names: string[]): Promise<KnowledgeGraph> {
const graph = await this.loadGraph();
// Filter entities
const filteredEntities = graph.entities.filter(e => names.includes(e.name));
// Create a Set of filtered entity names for quick lookup
const filteredEntityNames = new Set(filteredEntities.map(e => e.name));
// Filter relations to only include those between filtered entities
const filteredRelations = graph.relations.filter(r =>
filteredEntityNames.has(r.from) && filteredEntityNames.has(r.to)
);
const filteredGraph: KnowledgeGraph = {
entities: filteredEntities,
relations: filteredRelations,
};
return filteredGraph;
}
}
let knowledgeGraphManager: KnowledgeGraphManager;
// The server instance and tools exposed to Claude
const server = new Server({
name: "memory-server",
version: "0.6.3",
}, {
capabilities: {
tools: {},
},
},);
server.setRequestHandler(ListToolsRequestSchema, async () => {
return {
tools: [
{
name: "create_entities",
description: "Create multiple new entities in the knowledge graph",
inputSchema: {
type: "object",
properties: {
entities: {
type: "array",
items: {
type: "object",
properties: {
name: { type: "string", description: "The name of the entity" },
entityType: { type: "string", description: "The type of the entity" },
observations: {
type: "array",
items: { type: "string" },
description: "An array of observation contents associated with the entity"
},
},
required: ["name", "entityType", "observations"],
additionalProperties: false,
},
},
},
required: ["entities"],
additionalProperties: false,
},
},
{
name: "create_relations",
description: "Create multiple new relations between entities in the knowledge graph. Relations should be in active voice",
inputSchema: {
type: "object",
properties: {
relations: {
type: "array",
items: {
type: "object",
properties: {
from: { type: "string", description: "The name of the entity where the relation starts" },
to: { type: "string", description: "The name of the entity where the relation ends" },
relationType: { type: "string", description: "The type of the relation" },
},
required: ["from", "to", "relationType"],
additionalProperties: false,
},
},
},
required: ["relations"],
additionalProperties: false,
},
},
{
name: "add_observations",
description: "Add new observations to existing entities in the knowledge graph",
inputSchema: {
type: "object",
properties: {
observations: {
type: "array",
items: {
type: "object",
properties: {
entityName: { type: "string", description: "The name of the entity to add the observations to" },
contents: {
type: "array",
items: { type: "string" },
description: "An array of observation contents to add"
},
},
required: ["entityName", "contents"],
additionalProperties: false,
},
},
},
required: ["observations"],
additionalProperties: false,
},
},
{
name: "delete_entities",
description: "Delete multiple entities and their associated relations from the knowledge graph",
inputSchema: {
type: "object",
properties: {
entityNames: {
type: "array",
items: { type: "string" },
description: "An array of entity names to delete"
},
},
required: ["entityNames"],
additionalProperties: false,
},
},
{
name: "delete_observations",
description: "Delete specific observations from entities in the knowledge graph",
inputSchema: {
type: "object",
properties: {
deletions: {
type: "array",
items: {
type: "object",
properties: {
entityName: { type: "string", description: "The name of the entity containing the observations" },
observations: {
type: "array",
items: { type: "string" },
description: "An array of observations to delete"
},
},
required: ["entityName", "observations"],
additionalProperties: false,
},
},
},
required: ["deletions"],
additionalProperties: false,
},
},
{
name: "delete_relations",
description: "Delete multiple relations from the knowledge graph",
inputSchema: {
type: "object",
properties: {
relations: {
type: "array",
items: {
type: "object",
properties: {
from: { type: "string", description: "The name of the entity where the relation starts" },
to: { type: "string", description: "The name of the entity where the relation ends" },
relationType: { type: "string", description: "The type of the relation" },
},
required: ["from", "to", "relationType"],
additionalProperties: false,
},
description: "An array of relations to delete"
},
},
required: ["relations"],
additionalProperties: false,
},
},
{
name: "read_graph",
description: "Read the entire knowledge graph",
inputSchema: {
type: "object",
properties: {},
additionalProperties: false,
},
},
{
name: "search_nodes",
description: "Search for nodes in the knowledge graph based on a query",
inputSchema: {
type: "object",
properties: {
query: { type: "string", description: "The search query to match against entity names, types, and observation content" },
},
required: ["query"],
additionalProperties: false,
},
},
{
name: "open_nodes",
description: "Open specific nodes in the knowledge graph by their names",
inputSchema: {
type: "object",
properties: {
names: {
type: "array",
items: { type: "string" },
description: "An array of entity names to retrieve",
},
},
required: ["names"],
additionalProperties: false,
},
},
],
};
});
server.setRequestHandler(CallToolRequestSchema, async (request) => {
const { name, arguments: args } = request.params;
if (name === "read_graph") {
return { content: [{ type: "text", text: JSON.stringify(await knowledgeGraphManager.readGraph(), null, 2) }] };
}
if (!args) {
throw new Error(`No arguments provided for tool: ${name}`);
}
switch (name) {
case "create_entities":
return { content: [{ type: "text", text: JSON.stringify(await knowledgeGraphManager.createEntities(args.entities as Entity[]), null, 2) }] };
case "create_relations":
return { content: [{ type: "text", text: JSON.stringify(await knowledgeGraphManager.createRelations(args.relations as Relation[]), null, 2) }] };
case "add_observations":
return { content: [{ type: "text", text: JSON.stringify(await knowledgeGraphManager.addObservations(args.observations as { entityName: string; contents: string[] }[]), null, 2) }] };
case "delete_entities":
await knowledgeGraphManager.deleteEntities(args.entityNames as string[]);
return { content: [{ type: "text", text: "Entities deleted successfully" }] };
case "delete_observations":
await knowledgeGraphManager.deleteObservations(args.deletions as { entityName: string; observations: string[] }[]);
return { content: [{ type: "text", text: "Observations deleted successfully" }] };
case "delete_relations":
await knowledgeGraphManager.deleteRelations(args.relations as Relation[]);
return { content: [{ type: "text", text: "Relations deleted successfully" }] };
case "search_nodes":
return { content: [{ type: "text", text: JSON.stringify(await knowledgeGraphManager.searchNodes(args.query as string), null, 2) }] };
case "open_nodes":
return { content: [{ type: "text", text: JSON.stringify(await knowledgeGraphManager.openNodes(args.names as string[]), null, 2) }] };
default:
throw new Error(`Unknown tool: ${name}`);
}
});
async function main() {
// Initialize memory file path with backward compatibility
MEMORY_FILE_PATH = await ensureMemoryFilePath();
// Initialize knowledge graph manager with the memory file path
knowledgeGraphManager = new KnowledgeGraphManager(MEMORY_FILE_PATH);
const transport = new StdioServerTransport();
await server.connect(transport);
console.error("Knowledge Graph MCP Server running on stdio");
}
main().catch((error) => {
console.error("Fatal error in main():", error);
process.exit(1);
});
