diff --git a/src/core/graph.ts b/src/core/graph.ts
index b66494e..6e82964 100644
--- a/src/core/graph.ts
+++ b/src/core/graph.ts
@@ -57,6 +57,12 @@ export function getConnections(nodeId: string): { incoming: (Edge & { node: Node
   };
 }
 
+export function getEdgesByNode(nodeId: string): Edge[] {
+  const db = getDb();
+  const rows = db.prepare('SELECT * FROM edges WHERE from_id = ? OR to_id = ?').all(nodeId, nodeId) as any[];
+  return rows.map(rowToEdge);
+}
+
 export function buildTree(rootId?: string): TreeNode[] {
   const db = getDb();
   const edges = db.prepare('SELECT * FROM edges').all() as any[];
diff --git a/src/mcp/index.ts b/src/mcp/index.ts
index 099ceac..09a20b6 100644
--- a/src/mcp/index.ts
+++ b/src/mcp/index.ts
@@ -1,8 +1,10 @@
 import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
 import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
 import { z } from 'zod/v3';
-import { query, listNodes, getNode, findNodeByPrefix, addNode, addEdge } from '../core/store';
-import { getConnections } from '../core/graph';
+import { query, listNodes, getNode, findNodeByPrefix, addNode, addEdge, removeNode, removeEdge, updateNode } from '../core/store';
+import { getConnections, getEdgesByNode } from '../core/graph';
+import { cosineSimilarity } from '../core/search/vector';
+import { getDb } from '../core/db';
 import { NodeKind, EdgeType } from '../types';
 
 function serialize(data: any): string {
@@ -113,6 +115,256 @@ server.tool(
   }
 );
 
+// --- memory_split ---
+server.tool(
+  'memory_split',
+  'Break a large node into smaller children, updating parent with a summary',
+  {
+    id: z.string().describe('Node ID to split'),
+    pieces: z.array(z.object({ title: z.string(), content: z.string() })).describe('Child pieces to create'),
+    summary: z.string().optional().describe('Optional summary to replace parent content'),
+  },
+  async ({ id, pieces, summary }) => {
+    const node = getNode(id) ?? findNodeByPrefix(id);
+    if (!node) return { content: [{ type: 'text' as const, text: serialize({ error: 'Node not found' }) }], isError: true };
+
+    if (summary !== undefined) {
+      await updateNode(node.id, { content: summary });
+    }
+
+    const children = [];
+    for (const piece of pieces) {
+      const child = await addNode({ kind: node.kind, title: piece.title, content: piece.content, tags: [...node.tags] });
+      addEdge(node.id, child.id, 'contains');
+      children.push(child);
+    }
+    return { content: [{ type: 'text' as const, text: serialize({ parent: node.id, children: children.map(c => ({ id: c.id, title: c.title })) }) }] };
+  }
+);
+
+// --- memory_merge ---
+server.tool(
+  'memory_merge',
+  'Merge multiple nodes into a single new node, relinking edges and deleting originals',
+  {
+    nodeIds: z.array(z.string()).describe('Node IDs to merge'),
+    title: z.string().describe('Title for merged node'),
+    content: z.string().describe('Content for merged node'),
+    kind: z.enum(['memory', 'component', 'task', 'decision']).optional().describe('Kind (defaults to first node\'s kind)'),
+  },
+  async ({ nodeIds, title, content, kind }) => {
+    const nodes = nodeIds.map(id => getNode(id) ?? findNodeByPrefix(id));
+    if (nodes.some(n => !n)) return { content: [{ type: 'text' as const, text: serialize({ error: 'One or more nodes not found' }) }], isError: true };
+
+    const validNodes = nodes as Exclude<typeof nodes[number], null>[];
+    const allTags = [...new Set(validNodes.flatMap(n => n.tags))];
+    const mergedKind = (kind as NodeKind) ?? validNodes[0].kind;
+
+    const merged = await addNode({ kind: mergedKind, title, content, tags: allTags });
+    const oldIds = new Set(validNodes.map(n => n.id));
+
+    // Relink edges from old nodes to merged node
+    const db = getDb();
+    for (const n of validNodes) {
+      const edges = getEdgesByNode(n.id);
+      for (const e of edges) {
+        const from = oldIds.has(e.fromId) ? merged.id : e.fromId;
+        const to = oldIds.has(e.toId) ? merged.id : e.toId;
+        if (from !== to) {
+          try { addEdge(from, to, e.type, e.metadata); } catch {}
+        }
+      }
+      removeNode(n.id, true);
+    }
+
+    return { content: [{ type: 'text' as const, text: serialize({ merged: { id: merged.id, title: merged.title, tags: merged.tags } }) }] };
+  }
+);
+
+// --- memory_dedupe ---
+server.tool(
+  'memory_dedupe',
+  'Find similar/duplicate nodes using embedding cosine similarity',
+  {
+    threshold: z.number().optional().describe('Similarity threshold (default 0.85)'),
+    kind: z.enum(['memory', 'component', 'task', 'decision']).optional().describe('Filter by kind'),
+    limit: z.number().optional().describe('Max groups to return (default 10)'),
+  },
+  async ({ threshold, kind, limit }) => {
+    const thresh = threshold ?? 0.85;
+    const maxGroups = limit ?? 10;
+    const nodes = listNodes({ kind: kind as NodeKind, includeStale: false });
+    const withEmb = nodes.filter(n => n.embedding);
+
+    const groups: { nodes: { id: string; title: string }[]; similarity: number }[] = [];
+    const seen = new Set<string>();
+
+    for (let i = 0; i < withEmb.length && groups.length < maxGroups; i++) {
+      if (seen.has(withEmb[i].id)) continue;
+      const group = [{ id: withEmb[i].id, title: withEmb[i].title }];
+      let maxSim = 0;
+      for (let j = i + 1; j < withEmb.length; j++) {
+        if (seen.has(withEmb[j].id)) continue;
+        const sim = cosineSimilarity(withEmb[i].embedding!, withEmb[j].embedding!);
+        if (sim >= thresh) {
+          group.push({ id: withEmb[j].id, title: withEmb[j].title });
+          seen.add(withEmb[j].id);
+          maxSim = Math.max(maxSim, sim);
+        }
+      }
+      if (group.length > 1) {
+        seen.add(withEmb[i].id);
+        groups.push({ nodes: group, similarity: maxSim });
+      }
+    }
+
+    return { content: [{ type: 'text' as const, text: serialize({ groups, count: groups.length }) }] };
+  }
+);
+
+// --- memory_prune ---
+server.tool(
+  'memory_prune',
+  'Clean up the graph: delete stale nodes, decay old nodes, or remove orphans',
+  {
+    mode: z.enum(['hard_delete_stale', 'decay_then_delete', 'delete_orphans']).describe('Prune mode'),
+    maxAgeDays: z.number().optional().describe('Max age in days for decay/delete modes'),
+  },
+  async ({ mode, maxAgeDays }) => {
+    const db = getDb();
+    let affected = 0;
+
+    if (mode === 'hard_delete_stale') {
+      const result = db.prepare('DELETE FROM nodes WHERE is_stale = 1').run();
+      affected = result.changes;
+    } else if (mode === 'decay_then_delete') {
+      const cutoff = Date.now() - (maxAgeDays ?? 90) * 86400000;
+      // First mark old non-stale as stale
+      const decayed = db.prepare('UPDATE nodes SET is_stale = 1, updated_at = ? WHERE is_stale = 0 AND last_accessed_at < ?').run(Date.now(), cutoff);
+      // Then hard-delete already-stale that are also old
+      const deleted = db.prepare('DELETE FROM nodes WHERE is_stale = 1 AND updated_at < ?').run(cutoff);
+      affected = decayed.changes + deleted.changes;
+    } else if (mode === 'delete_orphans') {
+      const orphans = db.prepare(`
+        SELECT n.id FROM nodes n
+        WHERE n.is_stale = 0
+        AND NOT EXISTS (SELECT 1 FROM edges e WHERE e.from_id = n.id OR e.to_id = n.id)
+      `).all() as any[];
+      for (const o of orphans) {
+        removeNode(o.id, true);
+      }
+      affected = orphans.length;
+    }
+
+    return { content: [{ type: 'text' as const, text: serialize({ mode, affected }) }] };
+  }
+);
+
+// --- memory_reorganize ---
+server.tool(
+  'memory_reorganize',
+  'Move a node under a new parent (updates contains edges)',
+  {
+    nodeId: z.string().describe('Node ID to move'),
+    newParentId: z.string().describe('New parent node ID'),
+  },
+  async ({ nodeId, newParentId }) => {
+    const node = getNode(nodeId) ?? findNodeByPrefix(nodeId);
+    const parent = getNode(newParentId) ?? findNodeByPrefix(newParentId);
+    if (!node) return { content: [{ type: 'text' as const, text: serialize({ error: 'Node not found' }) }], isError: true };
+    if (!parent) return { content: [{ type: 'text' as const, text: serialize({ error: 'Parent not found' }) }], isError: true };
+
+    // Remove existing incoming contains edges
+    const db = getDb();
+    const incomingContains = db.prepare('SELECT id FROM edges WHERE to_id = ? AND type = ?').all(node.id, 'contains') as any[];
+    for (const e of incomingContains) {
+      removeEdge(e.id);
+    }
+
+    const edge = addEdge(parent.id, node.id, 'contains');
+    return { content: [{ type: 'text' as const, text: serialize({ moved: node.id, newParent: parent.id, edge: edge.id }) }] };
+  }
+);
+
+// --- memory_bulk_tag ---
+server.tool(
+  'memory_bulk_tag',
+  'Add or remove tags on multiple nodes at once',
+  {
+    action: z.enum(['add', 'remove']).describe('Whether to add or remove tags'),
+    tags: z.array(z.string()).describe('Tags to add/remove'),
+    nodeIds: z.array(z.string()).optional().describe('Specific node IDs'),
+    filter: z.object({
+      kind: z.enum(['memory', 'component', 'task', 'decision']).optional(),
+      status: z.string().optional(),
+      tags: z.array(z.string()).optional(),
+    }).optional().describe('Filter to select nodes'),
+  },
+  async ({ action, tags, nodeIds, filter }) => {
+    let targets: { id: string; tags: string[] }[];
+
+    if (nodeIds?.length) {
+      targets = nodeIds.map(id => {
+        const n = getNode(id) ?? findNodeByPrefix(id);
+        return n ? { id: n.id, tags: n.tags } : null;
+      }).filter(Boolean) as { id: string; tags: string[] }[];
+    } else if (filter) {
+      targets = listNodes({ kind: filter.kind as NodeKind, status: filter.status, tags: filter.tags }).map(n => ({ id: n.id, tags: n.tags }));
+    } else {
+      return { content: [{ type: 'text' as const, text: serialize({ error: 'Provide nodeIds or filter' }) }], isError: true };
+    }
+
+    let modified = 0;
+    for (const t of targets) {
+      let newTags: string[];
+      if (action === 'add') {
+        newTags = [...new Set([...t.tags, ...tags])];
+      } else {
+        newTags = t.tags.filter(tag => !tags.includes(tag));
+      }
+      if (JSON.stringify(newTags) !== JSON.stringify(t.tags)) {
+        await updateNode(t.id, { tags: newTags });
+        modified++;
+      }
+    }
+
+    return { content: [{ type: 'text' as const, text: serialize({ action, tags, modified, total: targets.length }) }] };
+  }
+);
+
+// --- memory_stats ---
+server.tool(
+  'memory_stats',
+  'Get graph statistics: counts by kind, stale/orphan counts, tag distribution',
+  {},
+  async () => {
+    const db = getDb();
+
+    const byKind = db.prepare('SELECT kind, COUNT(*) as count FROM nodes WHERE is_stale = 0 GROUP BY kind').all();
+    const totalNodes = db.prepare('SELECT COUNT(*) as count FROM nodes WHERE is_stale = 0').get() as any;
+    const staleCount = db.prepare('SELECT COUNT(*) as count FROM nodes WHERE is_stale = 1').get() as any;
+    const edgeCount = db.prepare('SELECT COUNT(*) as count FROM edges').get() as any;
+    const edgesByType = db.prepare('SELECT type, COUNT(*) as count FROM edges GROUP BY type').all();
+    const orphanCount = db.prepare(`
+      SELECT COUNT(*) as count FROM nodes n
+      WHERE n.is_stale = 0
+      AND NOT EXISTS (SELECT 1 FROM edges e WHERE e.from_id = n.id OR e.to_id = n.id)
+    `).get() as any;
+    const tagDist = db.prepare('SELECT tag, COUNT(*) as count FROM node_tags GROUP BY tag ORDER BY count DESC LIMIT 20').all();
+
+    return {
+      content: [{
+        type: 'text' as const,
+        text: serialize({
+          nodes: { total: totalNodes.count, stale: staleCount.count, orphans: orphanCount.count, byKind },
+          edges: { total: edgeCount.count, byType: edgesByType },
+          topTags: tagDist,
+        }),
+      }],
+    };
+  }
+);
+
 async function main() {
   const transport = new StdioServerTransport();
   await server.connect(transport);