diff --git a/src/index.js b/src/index.js
index 924626f..a4a3e10 100644
--- a/src/index.js
+++ b/src/index.js
@@ -34,7 +34,7 @@ const mobilePaymentService = new MobilePaymentService(
   walletService,
 );
 const agentService = new AgentService(db);
-const a2aService = new A2AService(walletService, db);
+const a2aService = new A2AService(walletService, db, config);
 const ucpService = new UCPService(a2aService);
 
 // Initialize Express app
diff --git a/src/services/a2aService.js b/src/services/a2aService.js
index 73c4443..3c5c9d9 100644
--- a/src/services/a2aService.js
+++ b/src/services/a2aService.js
@@ -27,6 +27,7 @@ class A2AService {
    * @param {number} params.amount - Amount to transfer
    * @param {string} params.mandate - Optional signed Mandate (AP2) for Zero Trust validation
    * @param {Object} params.ucpPayload - The original UCP intent/payload
+   * @param {string} params.mandate - Optional signed Mandate (AP2) for Zero Trust validation
    */
   async executeTransfer({
     fromAgentId,
diff --git a/src/services/agent.js b/src/services/agent.js
index c1be719..63a4a71 100644
--- a/src/services/agent.js
+++ b/src/services/agent.js
@@ -177,15 +177,27 @@ class AgentService {
     // In a real system, this would involve interaction with the WalletService,
     // and policy checks for both agents.
     const fromAgent = await this.getAgent(fromAgentId);
-    const toAgent = await this.getAgent(toAgentId);
+    await this.getAgent(toAgentId); // Verify toAgent exists
 
-    // Basic policy checks (more complex logic would be here)
-    if (amount > fromAgent.policy.spendingLimit) {
-      throw new Error(`Zero Trust Validation Failed: Transfer amount exceeds spending limit for agent ${fromAgentId}`);
+    // Basic policy checks
+    const config = fromAgent.config || {};
+    const limits = config.limits || {};
+    const perTransactionLimit = limits.perTransaction || 0;
+
+    if (perTransactionLimit > 0 && amount > perTransactionLimit) {
+      throw new Error(
+        `Zero Trust Validation Failed: Transfer amount ${amount} exceeds per-transaction limit of ${perTransactionLimit} for agent ${fromAgentId}`,
+      );
     }
-    if (!fromAgent.policy.authorizedCounterparties.includes(toAgentId) &&
-        fromAgent.policy.authorizedCounterparties.length > 0) {
-      throw new Error(`Zero Trust Validation Failed: Agent ${toAgentId} is not an authorized counterparty for ${fromAgentId}`);
+
+    const authorizedCounterparties = config.authorizedCounterparties || [];
+    if (
+      authorizedCounterparties.length > 0 &&
+      !authorizedCounterparties.includes(toAgentId)
+    ) {
+      throw new Error(
+        `Zero Trust Validation Failed: Agent ${toAgentId} is not an authorized counterparty for ${fromAgentId}`,
+      );
     }
 
     // Simulate transfer success
diff --git a/src/services/mandate.js b/src/services/mandate.js
index 20feda1..df7e827 100644
--- a/src/services/mandate.js
+++ b/src/services/mandate.js
@@ -105,14 +105,42 @@ class MandateService {
   /**
    * Verify a Mandate (Intent or Cart)
    * @param {string} token - Signed JWT Mandate
+   * @param {Object} context - Optional context for validation (amount, recipient)
    * @returns {Promise<Object>} Decoded mandate payload
    */
-  async verifyMandate(token) {
+  async verifyMandate(token, context = {}) {
+    let decoded;
     try {
-      return jwt.verify(token, this.signingKey, { algorithms: ["HS256"] });
+      decoded = jwt.verify(token, this.signingKey, { algorithms: ["HS256"] });
     } catch (error) {
-      throw new Error(`Zero Trust Validation Failed: Mandate verification failed: ${error.message}`);
+      throw new Error(
+        `Zero Trust Validation Failed: Mandate verification failed: ${error.message}`,
+      );
     }
+
+    // Contextual Validation
+    if (context.amount) {
+      if (decoded.max_budget && context.amount > decoded.max_budget.value) {
+        throw new Error(
+          `Zero Trust Validation Failed: Amount ${context.amount} exceeds mandate budget of ${decoded.max_budget.value}`,
+        );
+      }
+      if (decoded.total_price && context.amount !== decoded.total_price) {
+        throw new Error(
+          `Zero Trust Validation Failed: Amount ${context.amount} does not match cart mandate total of ${decoded.total_price}`,
+        );
+      }
+    }
+
+    if (context.recipient && decoded.allowed_merchants?.length > 0) {
+      if (!decoded.allowed_merchants.includes(context.recipient)) {
+        throw new Error(
+          `Zero Trust Validation Failed: Recipient ${context.recipient} not authorized by mandate`,
+        );
+      }
+    }
+
+    return decoded;
   }
 
   /**
diff --git a/tests/unit/a2a.spec.js b/tests/unit/a2a.spec.js
new file mode 100644
index 0000000..bd89434
--- /dev/null
+++ b/tests/unit/a2a.spec.js
@@ -0,0 +1,94 @@
+const A2AService = require('../../src/services/a2aService');
+const MandateService = require('../../src/services/mandate');
+
+describe('A2AService', () => {
+  let a2aService;
+  let mockWalletService;
+  let mockDb;
+  let mandateService;
+  let validMandate;
+
+  beforeAll(async () => {
+    mandateService = new MandateService({ signingKey: 'test-secret' });
+    validMandate = await mandateService.issueIntentMandate({
+      userDid: 'did:key:user',
+      agentDid: 'did:key:agent1',
+      maxBudget: 1000
+    });
+  });
+
+  beforeEach(() => {
+    mockWalletService = {
+      transfer: jest.fn().mockResolvedValue({ success: true, transferId: 'tx123' })
+    };
+    mockDb = {
+      findAgentById: jest.fn()
+    };
+    a2aService = new A2AService(mockWalletService, mockDb, {
+      mandateConfig: { signingKey: 'test-secret' },
+      strictMandateMode: true
+    });
+  });
+
+  describe('executeTransfer', () => {
+    it('should throw error if mandate is missing in strict mode', async () => {
+      await expect(a2aService.executeTransfer({
+        fromAgentId: 'agent1',
+        toAgentId: 'agent2',
+        amount: 100
+      })).rejects.toThrow('Zero Trust Validation Failed: Mandate required for A2A transfer in strict mode');
+    });
+
+    it('should throw error if mandate is invalid', async () => {
+      await expect(a2aService.executeTransfer({
+        fromAgentId: 'agent1',
+        toAgentId: 'agent2',
+        amount: 100,
+        mandate: 'invalid-token'
+      })).rejects.toThrow(/Zero Trust Validation Failed: Mandate verification failed/);
+    });
+
+    it('should execute transfer when mandate is valid and agents exist', async () => {
+      const fromAgent = {
+        id: 'agent1',
+        name: 'Agent 1',
+        status: 'active',
+        walletId: 'wallet1',
+        config: { limits: { perTransaction: 500 } }
+      };
+      const toAgent = {
+        id: 'agent2',
+        name: 'Agent 2',
+        status: 'active',
+        walletId: 'wallet2'
+      };
+
+      mockDb.findAgentById.mockImplementation((id) => {
+        if (id === 'agent1') return fromAgent;
+        if (id === 'agent2') return toAgent;
+        return null;
+      });
+
+      const result = await a2aService.executeTransfer({
+        fromAgentId: 'agent1',
+        toAgentId: 'agent2',
+        amount: 100,
+        mandate: validMandate
+      });
+
+      expect(result.success).toBe(true);
+      expect(mockWalletService.transfer).toHaveBeenCalled();
+    });
+
+    it('should throw error if agent is not found', async () => {
+        mockDb.findAgentById.mockResolvedValue(null);
+
+        await expect(a2aService.executeTransfer({
+          fromAgentId: 'agent1',
+          toAgentId: 'agent2',
+          amount: 100,
+          mandate: validMandate
+        })).rejects.toThrow('Zero Trust Validation Failed: Sender agent agent1 not found or inactive');
+      });
+  });
+});
diff --git a/tests/unit/agent.spec.js b/tests/unit/agent.spec.js
index d4ea2da..49a8df6 100644
--- a/tests/unit/agent.spec.js
+++ b/tests/unit/agent.spec.js
@@ -38,4 +38,51 @@ describe('AgentService', () => {
       await expect(agentService.getAgent('nonexistent')).rejects.toThrow('Zero Trust Validation Failed: Agent not found');
     });
   });
+
+  describe('performA2ATransfer', () => {
+    it('should throw if amount exceeds perTransaction limit', async () => {
+      mockDb.findAgentById.mockResolvedValue({
+        id: 'agent1',
+        config: { limits: { perTransaction: 50 } },
+        status: 'active',
+      });
+
+      await expect(agentService.performA2ATransfer({
+        fromAgentId: 'agent1',
+        toAgentId: 'agent2',
+        amount: 100
+      })).rejects.toThrow(/Zero Trust Validation Failed: Transfer amount 100 exceeds per-transaction limit of 50/);
+    });
+
+    it('should throw if counterparty is not authorized', async () => {
+      mockDb.findAgentById.mockImplementation((id) => {
+        if (id === 'agent1') return {
+          id: 'agent1',
+          config: { authorizedCounterparties: ['agent3'] },
+          status: 'active',
+        };
+        return { id: id, status: 'active' };
+      });
+
+      await expect(agentService.performA2ATransfer({
+        fromAgentId: 'agent1',
+        toAgentId: 'agent2',
+        amount: 10
+      })).rejects.toThrow(/Zero Trust Validation Failed: Agent agent2 is not an authorized counterparty/);
+    });
+
+    it('should not throw if config is missing (graceful handling)', async () => {
+      mockDb.findAgentById.mockImplementation((id) => {
+        return { id: id, status: 'active' }; // No config
+      });
+
+      const result = await agentService.performA2ATransfer({
+        fromAgentId: 'agent1',
+        toAgentId: 'agent2',
+        amount: 10
+      });
+
+      expect(result.success).toBe(true);
+    });
+  });
 });