diff --git a/.changeset/mfjs-schema-sanitize.md b/.changeset/mfjs-schema-sanitize.md
new file mode 100644
index 0000000000..cd29fdb42b
--- /dev/null
+++ b/.changeset/mfjs-schema-sanitize.md
@@ -0,0 +1,6 @@
+---
+"@moonshot-ai/agent-core-v2": patch
+"@moonshot-ai/kimi-code": patch
+---
+
+Sanitize circular and non-standard MCP JSON schemas and map disabled field to enabled in MCP config.
diff --git a/packages/agent-core-v2/src/mcpCore/config-schema.ts b/packages/agent-core-v2/src/mcpCore/config-schema.ts
index 83afa8c70c..7ddb5a38b7 100644
--- a/packages/agent-core-v2/src/mcpCore/config-schema.ts
+++ b/packages/agent-core-v2/src/mcpCore/config-schema.ts
@@ -57,7 +57,10 @@ const McpServerConfigDiscriminatedSchema = z.discriminatedUnion('transport', [
 
 export const McpServerConfigSchema = z.preprocess((raw) => {
   if (typeof raw !== 'object' || raw === null || Array.isArray(raw)) return raw;
-  const obj = raw as Record<string, unknown>;
+  const obj = { ...(raw as Record<string, unknown>) };
+  if ('disabled' in obj && !('enabled' in obj) && typeof obj['disabled'] === 'boolean') {
+    obj['enabled'] = !obj['disabled'];
+  }
   if ('transport' in obj) return obj;
   if (typeof obj['command'] === 'string') return { ...obj, transport: 'stdio' };
   if (typeof obj['url'] === 'string') return { ...obj, transport: 'http' };
diff --git a/packages/agent-core-v2/src/mcpCore/connection-manager.ts b/packages/agent-core-v2/src/mcpCore/connection-manager.ts
index 8774de86f6..4d43f68186 100644
--- a/packages/agent-core-v2/src/mcpCore/connection-manager.ts
+++ b/packages/agent-core-v2/src/mcpCore/connection-manager.ts
@@ -11,6 +11,7 @@ import { SseMcpClient } from './client-sse';
 import type { UnexpectedCloseReason } from './client-shared';
 import { StdioMcpClient } from './client-stdio';
 import type { McpOAuthService } from '#/mcpCore/oauth/service';
+import { sanitizeMcpSchema } from './schema-sanitize';
 import { assertMcpInputSchema, type MCPClient, type MCPToolDefinition } from './types';
 
 export type McpServerStatus = 'pending' | 'connected' | 'failed' | 'disabled' | 'needs-auth' | 'removed';
@@ -451,7 +452,7 @@ export class McpConnectionManager implements McpConnectionView {
       tools: mcpTools.map((mcpTool) => ({
         name: mcpTool.name,
         description: mcpTool.description,
-        parameters: assertMcpInputSchema(mcpTool.name, mcpTool.inputSchema),
+        parameters: sanitizeMcpSchema(assertMcpInputSchema(mcpTool.name, mcpTool.inputSchema)),
       })),
     };
   }
diff --git a/packages/agent-core-v2/src/mcpCore/schema-sanitize.ts b/packages/agent-core-v2/src/mcpCore/schema-sanitize.ts
new file mode 100644
index 0000000000..b25324e70b
--- /dev/null
+++ b/packages/agent-core-v2/src/mcpCore/schema-sanitize.ts
@@ -0,0 +1,237 @@
+type Json = string | number | boolean | null | Json[] | { [key: string]: Json };
+type JsonRecord = Record<string, Json>;
+
+const COMBINATOR_KEYS = [
+  'anyOf',
+  'oneOf',
+  'allOf',
+  'not',
+  'if',
+  'then',
+  'else',
+  '$ref',
+] as const;
+
+const OBJECT_KEYWORDS = [
+  'properties',
+  'additionalProperties',
+  'patternProperties',
+  'propertyNames',
+  'required',
+  'minProperties',
+  'maxProperties',
+] as const;
+
+const ARRAY_KEYWORDS = [
+  'items',
+  'prefixItems',
+  'minItems',
+  'maxItems',
+  'uniqueItems',
+  'contains',
+] as const;
+
+const STRING_KEYWORDS = ['minLength', 'maxLength', 'pattern', 'format'] as const;
+
+const NUMERIC_KEYWORDS = [
+  'minimum',
+  'maximum',
+  'multipleOf',
+  'exclusiveMinimum',
+  'exclusiveMaximum',
+] as const;
+
+function decodePointerSegment(segment: string): string {
+  return segment.replace(/~1/g, '/').replace(/~0/g, '~');
+}
+
+function jsonTypeOf(value: Json): string {
+  if (typeof value === 'boolean') return 'boolean';
+  if (typeof value === 'number') return Number.isInteger(value) ? 'integer' : 'number';
+  if (typeof value === 'string') return 'string';
+  if (value === null) return 'null';
+  if (Array.isArray(value)) return 'array';
+  if (typeof value === 'object') return 'object';
+  return 'string';
+}
+
+function derefJsonSchema(schema: JsonRecord): JsonRecord {
+  const root = structuredClone(schema);
+
+  function resolvePointer(pointer: string): Json {
+    const pathStr = pointer.replace(/^#\/?/, '');
+    if (pathStr === '') {
+      return root;
+    }
+    const parts = pathStr.split('/').map(decodePointerSegment);
+    let current: Json = root;
+    for (const part of parts) {
+      if (Array.isArray(current)) {
+        if (!/^(0|[1-9][0-9]*)$/.test(part)) {
+          throw new Error(`Unable to resolve reference path: ${pointer}`);
+        }
+        const index = Number(part);
+        if (index < 0 || index >= current.length) {
+          throw new Error(`Unable to resolve reference path: ${pointer}`);
+        }
+        current = current[index] as Json;
+        continue;
+      }
+      if (typeof current !== 'object' || current === null) {
+        throw new Error(`Unable to resolve reference path: ${pointer}`);
+      }
+      if (!(part in (current as JsonRecord))) {
+        throw new Error(`Unable to resolve reference path: ${pointer}`);
+      }
+      current = (current as JsonRecord)[part] as Json;
+    }
+    return current;
+  }
+
+  function traverse(node: Json, activeRefs: Set<string> = new Set()): Json {
+    if (Array.isArray(node)) {
+      return node.map((item) => traverse(item, activeRefs));
+    }
+    if (typeof node !== 'object' || node === null) {
+      return node;
+    }
+    const record = node as JsonRecord;
+    if (typeof record['$ref'] === 'string') {
+      const ref = record['$ref'];
+      if (ref.startsWith('#')) {
+        if (activeRefs.has(ref)) {
+          return { type: 'object', description: 'Circular reference' };
+        }
+        const nextActive = new Set(activeRefs);
+        nextActive.add(ref);
+        const target = traverse(resolvePointer(ref), nextActive);
+        if (typeof target !== 'object' || target === null || Array.isArray(target)) {
+          throw new Error('Local $ref must resolve to a JSON object');
+        }
+        const { $ref: _, ...rest } = record;
+        const traversedRest: JsonRecord = {};
+        for (const [key, value] of Object.entries(rest)) {
+          traversedRest[key] = traverse(value, nextActive);
+        }
+        return { ...(target as JsonRecord), ...traversedRest };
+      }
+      return record;
+    }
+    const result: JsonRecord = {};
+    for (const [key, value] of Object.entries(record)) {
+      result[key] = traverse(value, activeRefs);
+    }
+    return result;
+  }
+
+  const resolved = traverse(root) as JsonRecord;
+  delete resolved['$defs'];
+  delete resolved['definitions'];
+  return resolved;
+}
+
+function splitMixedEnum(values: Json[]): JsonRecord[] {
+  const buckets = new Map<string, Json[]>();
+  for (const value of values) {
+    const t = jsonTypeOf(value);
+    const list = buckets.get(t) ?? [];
+    list.push(value);
+    buckets.set(t, list);
+  }
+  if (buckets.has('integer') && buckets.has('number')) {
+    const merged = [...(buckets.get('integer') ?? []), ...(buckets.get('number') ?? [])];
+    buckets.delete('integer');
+    buckets.set('number', merged);
+  }
+  return [...buckets.entries()].map(([type, enumValues]) => ({
+    type,
+    enum: enumValues,
+  }));
+}
+
+function inferTypeFromStructure(node: JsonRecord): string {
+  if (OBJECT_KEYWORDS.some((k) => k in node)) return 'object';
+  if (ARRAY_KEYWORDS.some((k) => k in node)) return 'array';
+  if (STRING_KEYWORDS.some((k) => k in node)) return 'string';
+  if (NUMERIC_KEYWORDS.some((k) => k in node)) return 'number';
+  return 'string';
+}
+
+function normalizeProperty(node: Json): void {
+  if (typeof node !== 'object' || node === null || Array.isArray(node)) return;
+  const record = node as JsonRecord;
+
+  if (!('type' in record) && !COMBINATOR_KEYS.some((key) => key in record)) {
+    const enumValues = record['enum'];
+    if (Array.isArray(enumValues) && enumValues.length > 0) {
+      const types = new Set(enumValues.map((v) => jsonTypeOf(v)));
+      if (types.size === 1) {
+        record['type'] = [...types][0]!;
+      } else if (types.size === 2 && types.has('integer') && types.has('number')) {
+        record['type'] = 'number';
+      } else {
+        record['anyOf'] = splitMixedEnum(enumValues);
+        delete record['enum'];
+      }
+    } else if ('const' in record) {
+      record['type'] = jsonTypeOf(record['const'] as Json);
+    } else {
+      record['type'] = inferTypeFromStructure(record);
+    }
+  }
+
+  recurseSchema(record);
+}
+
+function recurseSchema(node: Json): void {
+  if (typeof node !== 'object' || node === null || Array.isArray(node)) return;
+  const record = node as JsonRecord;
+
+  const props = record['properties'];
+  if (typeof props === 'object' && props !== null && !Array.isArray(props)) {
+    for (const value of Object.values(props as JsonRecord)) {
+      normalizeProperty(value);
+    }
+  }
+
+  const items = record['items'];
+  if (Array.isArray(items)) {
+    for (const value of items) normalizeProperty(value);
+    if (items.length === 0) {
+      delete record['items'];
+    } else if (items.length === 1) {
+      record['items'] = items[0] as Json;
+    } else {
+      record['items'] = { anyOf: items };
+    }
+  } else if (typeof items === 'object' && items !== null) {
+    normalizeProperty(items);
+  }
+
+  const prefixItems = record['prefixItems'];
+  if (Array.isArray(prefixItems)) {
+    for (const value of prefixItems) normalizeProperty(value);
+  }
+
+  const additional = record['additionalProperties'];
+  if (typeof additional === 'object' && additional !== null && !Array.isArray(additional)) {
+    normalizeProperty(additional);
+  }
+
+  for (const key of ['anyOf', 'oneOf', 'allOf'] as const) {
+    const branches = record[key];
+    if (Array.isArray(branches)) {
+      for (const value of branches) normalizeProperty(value);
+    }
+  }
+}
+
+export function sanitizeMcpSchema(schema: unknown): Record<string, unknown> {
+  if (typeof schema !== 'object' || schema === null || Array.isArray(schema)) {
+    return schema as Record<string, unknown>;
+  }
+  const dereffed = derefJsonSchema(schema as JsonRecord);
+  const cloned = structuredClone(dereffed);
+  recurseSchema(cloned);
+  return cloned;
+}
diff --git a/packages/agent-core-v2/test/mcpCore/schema-sanitize.test.ts b/packages/agent-core-v2/test/mcpCore/schema-sanitize.test.ts
new file mode 100644
index 0000000000..cf9b2df59b
--- /dev/null
+++ b/packages/agent-core-v2/test/mcpCore/schema-sanitize.test.ts
@@ -0,0 +1,216 @@
+import { describe, expect, it } from 'vitest';
+
+import { sanitizeMcpSchema } from '#/mcpCore/schema-sanitize';
+
+type Schema = Record<string, unknown>;
+
+function props(result: Schema): Record<string, Schema> {
+  return result['properties'] as Record<string, Schema>;
+}
+
+function prop(result: Schema, name: string): Schema {
+  return props(result)[name]!;
+}
+
+describe('sanitizeMcpSchema — non-object inputs', () => {
+  it('returns null unchanged', () => {
+    expect(sanitizeMcpSchema(null)).toBe(null);
+  });
+
+  it('returns arrays unchanged', () => {
+    expect(sanitizeMcpSchema([1, 2, 3])).toEqual([1, 2, 3]);
+  });
+
+  it('returns primitives unchanged', () => {
+    expect(sanitizeMcpSchema('string')).toBe('string');
+    expect(sanitizeMcpSchema(42)).toBe(42);
+    expect(sanitizeMcpSchema(true)).toBe(true);
+  });
+});
+
+describe('sanitizeMcpSchema — missing type filling', () => {
+  it('fills in string when no type and no structural hints', () => {
+    const result = sanitizeMcpSchema({
+      type: 'object',
+      properties: {
+        name: { description: 'User name' },
+      },
+    });
+    expect(prop(result, 'name')['type']).toBe('string');
+  });
+
+  it('infers type from enum values', () => {
+    const result = sanitizeMcpSchema({
+      type: 'object',
+      properties: {
+        mode: { enum: ['fast', 'slow'] },
+        count: { enum: [1, 2, 3] },
+        enabled: { enum: [true, false] },
+      },
+    });
+    expect(prop(result, 'mode')['type']).toBe('string');
+    expect(prop(result, 'count')['type']).toBe('integer');
+    expect(prop(result, 'enabled')['type']).toBe('boolean');
+  });
+
+  it('infers type from const value', () => {
+    const result = sanitizeMcpSchema({
+      type: 'object',
+      properties: {
+        kind: { const: 'user' },
+        timeout: { const: 30 },
+      },
+    });
+    expect(prop(result, 'kind')['type']).toBe('string');
+    expect(prop(result, 'timeout')['type']).toBe('integer');
+  });
+
+  it('infers type from structural keywords', () => {
+    const result = sanitizeMcpSchema({
+      type: 'object',
+      properties: {
+        objProp: { properties: { a: {} } },
+        arrProp: { items: { type: 'string' } },
+        strProp: { pattern: '^\\w+$' },
+        numProp: { minimum: 0 },
+      },
+    });
+    expect(prop(result, 'objProp')['type']).toBe('object');
+    expect(prop(result, 'arrProp')['type']).toBe('array');
+    expect(prop(result, 'strProp')['type']).toBe('string');
+    expect(prop(result, 'numProp')['type']).toBe('number');
+  });
+
+  it('does not add type when a combinator key is present', () => {
+    const result = sanitizeMcpSchema({
+      type: 'object',
+      properties: {
+        any: { anyOf: [{ type: 'string' }, { type: 'null' }] },
+        one: { oneOf: [{ type: 'string' }, { type: 'number' }] },
+        all: { allOf: [{ type: 'string' }] },
+        not: { not: { type: 'string' } },
+      },
+    });
+    expect(prop(result, 'any')['type']).toBeUndefined();
+    expect(prop(result, 'one')['type']).toBeUndefined();
+    expect(prop(result, 'all')['type']).toBeUndefined();
+    expect(prop(result, 'not')['type']).toBeUndefined();
+  });
+});
+
+describe('sanitizeMcpSchema — tuple items to object', () => {
+  it('converts tuple items array to anyOf object', () => {
+    const result = sanitizeMcpSchema({
+      type: 'object',
+      properties: {
+        size: {
+          type: 'array',
+          items: [{ type: 'number' }, { type: 'number' }],
+        },
+      },
+    });
+    const sizeProp = prop(result, 'size');
+    expect(typeof sizeProp['items']).toBe('object');
+    expect(Array.isArray(sizeProp['items'])).toBe(false);
+    expect(sizeProp['items']).toEqual({
+      anyOf: [{ type: 'number' }, { type: 'number' }],
+    });
+  });
+
+  it('unwraps single-element tuple items array to single schema object', () => {
+    const result = sanitizeMcpSchema({
+      type: 'object',
+      properties: {
+        tags: {
+          type: 'array',
+          items: [{ type: 'string' }],
+        },
+      },
+    });
+    const tagsProp = prop(result, 'tags');
+    expect(tagsProp['items']).toEqual({ type: 'string' });
+  });
+});
+
+describe('sanitizeMcpSchema — mixed enums', () => {
+  it('splits mixed type enum into typed anyOf branches', () => {
+    const result = sanitizeMcpSchema({
+      type: 'object',
+      properties: {
+        mixed: { enum: ['a', 1, true] },
+      },
+    });
+    const mixed = prop(result, 'mixed');
+    expect(mixed['anyOf']).toEqual([
+      { type: 'string', enum: ['a'] },
+      { type: 'integer', enum: [1] },
+      { type: 'boolean', enum: [true] },
+    ]);
+  });
+});
+
+describe('sanitizeMcpSchema — recursive and circular schemas', () => {
+  it('inlines local $ref and removes definitions buckets', () => {
+    const schema = {
+      type: 'object',
+      properties: {
+        user: { $ref: '#/definitions/User' },
+      },
+      definitions: {
+        User: {
+          type: 'object',
+          properties: {
+            name: { type: 'string' },
+          },
+        },
+      },
+    };
+    const result = sanitizeMcpSchema(schema);
+    expect('definitions' in result).toBe(false);
+    expect(prop(result, 'user')).toEqual({
+      type: 'object',
+      properties: {
+        name: { type: 'string' },
+      },
+    });
+  });
+
+  it('handles circular references without throwing', () => {
+    const schema = {
+      type: 'object',
+      properties: {
+        node: { $ref: '#/definitions/Node' },
+      },
+      definitions: {
+        Node: {
+          type: 'object',
+          properties: {
+            parent: { $ref: '#/definitions/Node' },
+          },
+        },
+      },
+    };
+    const result = sanitizeMcpSchema(schema);
+    expect('definitions' in result).toBe(false);
+    const nodeProp = prop(result, 'node');
+    expect(nodeProp['type']).toBe('object');
+    const parentProp = prop(nodeProp, 'parent');
+    expect(parentProp['type']).toBe('object');
+    expect(parentProp['description']).toBe('Circular reference');
+  });
+
+  it('handles root self-reference safely', () => {
+    const schema = {
+      type: 'object',
+      properties: {
+        self: { $ref: '#' },
+      },
+    };
+    const result = sanitizeMcpSchema(schema);
+    const selfProp = prop(result, 'self');
+    expect(selfProp['type']).toBe('object');
+    const nestedSelf = prop(selfProp, 'self');
+    expect(nestedSelf['type']).toBe('object');
+    expect(nestedSelf['description']).toBe('Circular reference');
+  });
+});