diff --git a/tests/boundary/mcp/analysisViewMcp.test.ts b/tests/boundary/mcp/analysisViewMcp.test.ts
index 6d95d6f85f..3cc51ae163 100644
--- a/tests/boundary/mcp/analysisViewMcp.test.ts
+++ b/tests/boundary/mcp/analysisViewMcp.test.ts
@@ -1,3 +1,4 @@
+import { createMcpSchemaValidation } from "../../fixtures/mcpSchemaValidation.js";
 import { advertisedMcpToolSchemas } from "../../fixtures/advertisedMcpTool.js";
 import { API_SURFACE_EXAMPLE } from "../../../src/contracts/analysisViewApiSurfaceExample.js";
 import { ENVIRONMENT_MANIFEST_EXAMPLE } from "../../../src/contracts/analysisViewEnvironmentManifestExample.js";
@@ -14,8 +15,7 @@ import { createTestTempDirectory } from "../../fixtures/temporaryDirectory.js";
 import { parseMcpToolError } from "../../fixtures/mcpToolError.js";
 import { Client, InMemoryTransport } from "@modelcontextprotocol/client";
 import { STDIO_DEFAULT_MAX_BUFFER_SIZE } from "@modelcontextprotocol/server";
-import { Ajv2020 } from "ajv/dist/2020.js";
-import { expect, it, onTestFinished } from "vitest";
+import { afterAll, expect, it, onTestFinished } from "vitest";
 import { z } from "zod";
 
 import { BinaryLayoutService } from "../../../src/application/binaryDiagnostics/BinaryLayoutService.js";
@@ -51,6 +51,9 @@ import { wasmArtifactFixture } from "../../fixtures/wasm/artifact.js";
 import { evmInterfaceFixture } from "../../fixtures/evm/interface.js";
 import type { RelationshipCoverage } from "../../../src/domain/relationshipCoverage.js";
 
+const schemaValidation = createMcpSchemaValidation();
+afterAll(() => schemaValidation.clear());
+
 const connect = async (
   binaryLayout?: BinaryLayoutService,
   webNetworkCapture?: WebNetworkCaptureService,
@@ -67,7 +70,10 @@ const connect = async (
       ...(webNetworkCapture === undefined ? {} : { webNetworkCapture }),
     },
   );
-  const client = new Client({ name: "analysis-view-mcp", version: "1" });
+  const client = new Client(
+    { name: "analysis-view-mcp", version: "1" },
+    { jsonSchemaValidator: schemaValidation },
+  );
   onTestFinished(async () => {
     await client.close();
     await server.close();
@@ -85,6 +91,7 @@ it("preserves native relationship coverage through inline and retained MCP views
   const { ajv, outputSchema } = await advertisedMcpToolSchemas(
     client,
     "inspect_analysis_view",
+    schemaValidation.assertions,
   );
   const coverages: (RelationshipCoverage | undefined)[] = [
     {
@@ -156,6 +163,7 @@ it("advertises typed module references and preserves portable/retained Evidence
   const { ajv, inputSchema, outputSchema } = await advertisedMcpToolSchemas(
     client,
     "inspect_analysis_view",
+    schemaValidation.assertions,
   );
   const view = {
     kind: "javascript",
@@ -407,6 +415,7 @@ it("advertises exact schemas and projects one layout section from retained Evide
   const { ajv, inputSchema, outputSchema } = await advertisedMcpToolSchemas(
     client,
     "inspect_analysis_view",
+    schemaValidation.assertions,
   );
   expect(
     ajv.validate(inputSchema, {
@@ -758,7 +767,7 @@ it("delivers a bounded native dossier view over MCP without a Ghidra provider or
   );
   if (advertised?.outputSchema === undefined)
     throw new Error("missing view schemas");
-  const ajv = new Ajv2020({ strict: false, validateFormats: false });
+  const ajv = schemaValidation.assertions;
   const inputSchema: Record<string, unknown> = advertised.inputSchema;
   const outputSchema: Record<string, unknown> = advertised.outputSchema;
   const arguments_ = {
@@ -1232,6 +1241,7 @@ it("extracts an environment state identically from retained, portable and file M
   const { ajv, inputSchema, outputSchema } = await advertisedMcpToolSchemas(
     client,
     "inspect_analysis_view",
+    schemaValidation.assertions,
   );
   const capture = environmentStateCaptureFixture();
   const parent = analysisViewCaptureEvidence(capture);
@@ -1305,6 +1315,7 @@ it("projects an environment manifest identically from retained, portable and fil
   const { ajv, inputSchema, outputSchema } = await advertisedMcpToolSchemas(
     client,
     "inspect_analysis_view",
+    schemaValidation.assertions,
   );
   const capture = environmentManifestCaptureFixture();
   const parent = analysisViewCaptureEvidence(capture);
diff --git a/tests/boundary/mcp/mcpSchemaValidation.test.ts b/tests/boundary/mcp/mcpSchemaValidation.test.ts
new file mode 100644
index 0000000000..2ce015a4f9
--- /dev/null
+++ b/tests/boundary/mcp/mcpSchemaValidation.test.ts
@@ -0,0 +1,87 @@
+import { expect, it } from "vitest";
+import { createMcpSchemaValidation } from "../../fixtures/mcpSchemaValidation.js";
+
+it("reuses equal schemas and recompiles changed schemas sharing an id", () => {
+  const validation = createMcpSchemaValidation();
+  try {
+    const schema = {
+      $schema: "https://json-schema.org/draft/2020-12/schema",
+      $id: "https://fixture.test/result",
+      type: "string" as "string" | "integer",
+    };
+    const first = validation.getValidator(schema);
+    expect(validation.getValidator(structuredClone(schema))).toBe(first);
+    expect(first("recorded").valid).toBe(true);
+    expect(first(42).valid).toBe(false);
+    expect(validation.assertions.validate(schema, "recorded")).toBe(true);
+    expect(validation.assertions.validate(schema, 42)).toBe(false);
+
+    schema.type = "integer";
+    const changed = validation.getValidator(schema);
+    expect(changed).not.toBe(first);
+    expect(changed(42).valid).toBe(true);
+    expect(changed("recorded").valid).toBe(false);
+    expect(validation.assertions.validate(schema, 42)).toBe(true);
+    expect(validation.assertions.validate(schema, "recorded")).toBe(false);
+
+    validation.clear();
+    expect(validation.getValidator(schema)).not.toBe(changed);
+  } finally {
+    validation.clear();
+  }
+});
+
+it("preserves SDK format validation and declared dialect dispatch", () => {
+  const validation = createMcpSchemaValidation();
+  try {
+    const schema = {
+      $schema: "http://json-schema.org/draft-07/schema#",
+      type: "string",
+      format: "email",
+    } as const;
+    const validator = validation.getValidator(schema);
+    expect(validator("analyst@example.test").valid).toBe(true);
+    expect(validator("invalid email").valid).toBe(false);
+    // Explicit schema assertions retain their separate format-off policy.
+    expect(
+      validation.assertions.validate(
+        { type: "string", format: "email" },
+        "invalid email",
+      ),
+    ).toBe(true);
+    expect(
+      validation.assertions.validateSchema({ type: "string", minLength: -1 }),
+    ).toBe(false);
+  } finally {
+    validation.clear();
+  }
+});
+
+it("owns nested schema values independently of later caller mutation", () => {
+  const validation = createMcpSchemaValidation();
+  try {
+    const schema = { enum: [{ state: "recorded" }, { state: "other" }] };
+    const originalSchema = structuredClone(schema);
+    const original = validation.getValidator(schema);
+    expect(validation.assertions.validate(schema, { state: "recorded" })).toBe(
+      true,
+    );
+    schema.enum[0]!.state = "changed";
+    const changed = validation.getValidator(schema);
+    expect(original({ state: "recorded" }).valid).toBe(true);
+    expect(original({ state: "changed" }).valid).toBe(false);
+    expect(changed({ state: "changed" }).valid).toBe(true);
+    expect(changed({ state: "recorded" }).valid).toBe(false);
+    expect(
+      validation.assertions.validate(originalSchema, { state: "recorded" }),
+    ).toBe(true);
+    expect(validation.assertions.validate(schema, { state: "recorded" })).toBe(
+      false,
+    );
+    expect(validation.assertions.validate(schema, { state: "changed" })).toBe(
+      true,
+    );
+  } finally {
+    validation.clear();
+  }
+});
diff --git a/tests/fixtures/advertisedMcpTool.ts b/tests/fixtures/advertisedMcpTool.ts
index e10e603e40..649dbb4865 100644
--- a/tests/fixtures/advertisedMcpTool.ts
+++ b/tests/fixtures/advertisedMcpTool.ts
@@ -5,17 +5,29 @@ import { toolContract } from "../../src/contracts/toolContracts.js";
 import { parseEvidence } from "../../src/domain/evidence.js";
 import type { BinarySession } from "../../src/application/binary/BinarySession.js";
 
-/** Verify the actual advertised schemas, retaining a private Ajv registry. */
+interface AdvertisedSchemaAssertions {
+  readonly errors: unknown;
+  validateSchema(schema: Record<string, unknown>): boolean | Promise<unknown>;
+  validate(
+    schema: Record<string, unknown>,
+    value: unknown,
+  ): boolean | Promise<unknown>;
+}
+
+/** Verify actual advertised schemas; callers may own file-local preparation. */
 export const advertisedMcpToolSchemas = async (
   client: Client,
   name: string,
+  ajv: AdvertisedSchemaAssertions = new Ajv2020({
+    strict: false,
+    validateFormats: false,
+  }),
 ) => {
   const advertised = (await client.listTools()).tools.find(
     (tool) => tool.name === name,
   );
   if (advertised?.outputSchema === undefined)
     throw new Error(`${name} must publish both schemas`);
-  const ajv = new Ajv2020({ strict: false, validateFormats: false });
   const inputSchema: Record<string, unknown> = advertised.inputSchema;
   const outputSchema: Record<string, unknown> = advertised.outputSchema;
   expect(ajv.validateSchema(inputSchema)).toBe(true);
diff --git a/tests/fixtures/mcpSchemaValidation.ts b/tests/fixtures/mcpSchemaValidation.ts
new file mode 100644
index 0000000000..67300764bb
--- /dev/null
+++ b/tests/fixtures/mcpSchemaValidation.ts
@@ -0,0 +1,60 @@
+import type {
+  JsonSchemaType,
+  JsonSchemaValidator,
+} from "@modelcontextprotocol/client";
+import { AjvJsonSchemaValidator } from "@modelcontextprotocol/client/validators/ajv";
+import { Ajv2020 } from "ajv/dist/2020.js";
+import type { ValidateFunction } from "ajv";
+
+/** Share immutable schema preparation within one test file, never its sessions. */
+export const createMcpSchemaValidation = () => {
+  const sdkValidators = new Map<string, JsonSchemaValidator<unknown>>();
+  const assertionValidators = new Map<string, ValidateFunction>();
+  const meta = new Ajv2020({ strict: false, validateFormats: false });
+  let errors: unknown = null;
+  return {
+    getValidator<T>(schema: JsonSchemaType): JsonSchemaValidator<T> {
+      const key = JSON.stringify(schema);
+      let validator = sdkValidators.get(key);
+      if (validator === undefined) {
+        // Each full schema owns its default provider, including dialect dispatch.
+        // Distinct schemas may legally reuse the same $id in separate servers.
+        validator = new AjvJsonSchemaValidator().getValidator(JSON.parse(key));
+        sdkValidators.set(key, validator);
+      }
+      return validator as JsonSchemaValidator<T>;
+    },
+    assertions: {
+      get errors() {
+        return errors;
+      },
+      validateSchema(schema: Record<string, unknown>) {
+        const valid = meta.validateSchema(schema);
+        errors = meta.errors;
+        return valid;
+      },
+      validate(schema: Record<string, unknown>, value: unknown) {
+        const key = JSON.stringify(schema);
+        let validator = assertionValidators.get(key);
+        if (validator === undefined) {
+          // Preserve the explicit assertions' existing options, independently
+          // of the SDK default provider's format/all-errors policy.
+          validator = new Ajv2020({
+            strict: false,
+            validateFormats: false,
+          }).compile(JSON.parse(key));
+          assertionValidators.set(key, validator);
+        }
+        const valid = validator(value);
+        errors = validator.errors;
+        return valid;
+      },
+    },
+    clear() {
+      sdkValidators.clear();
+      assertionValidators.clear();
+      meta.removeSchema();
+      errors = null;
+    },
+  };
+};