diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6d637ca..37167c4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.2.4] - 2026-02-01
+
+- Accept MCP arguments/input and validate payloads
+- Emit MCP image content with `data` + `mimeType` fields
+
 ## [0.2.3] - 2026-02-01
 
 - Harden MCP request handling
@@ -26,4 +31,3 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [0.1.0] - 2026-02-01
 
 - Initial release
-
diff --git a/bindings/python/pyproject.toml b/bindings/python/pyproject.toml
index b30ea06..c7b9082 100644
--- a/bindings/python/pyproject.toml
+++ b/bindings/python/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "mermkit"
-version = "0.2.3"
+version = "0.2.4"
 description = "Python bindings for mermkit (Mermaid rendering toolkit)"
 readme = "README.md"
 requires-python = ">=3.8"
diff --git a/bindings/rust/Cargo.toml b/bindings/rust/Cargo.toml
index bb159eb..6557668 100644
--- a/bindings/rust/Cargo.toml
+++ b/bindings/rust/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mermkit"
-version = "0.2.3"
+version = "0.2.4"
 edition = "2021"
 description = "Rust bindings for mermkit (Mermaid rendering toolkit)"
 license = "MIT"
diff --git a/package.json b/package.json
index b170c1b..1d7385e 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "mermkit",
   "private": true,
-  "version": "0.2.3",
+  "version": "0.2.4",
   "repository": {
     "type": "git",
     "url": "https://github.com/MermaidKit/mermkit.git"
diff --git a/packages/adapters/package.json b/packages/adapters/package.json
index ee0d625..b9be307 100644
--- a/packages/adapters/package.json
+++ b/packages/adapters/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@mermkit/adapters",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "repository": {
     "type": "git",
     "url": "https://github.com/MermaidKit/mermkit.git"
@@ -18,6 +18,6 @@
     "build": "tsc -b"
   },
   "dependencies": {
-    "@mermkit/core": "0.2.3"
+    "@mermkit/core": "0.2.4"
   }
 }
diff --git a/packages/cli/package.json b/packages/cli/package.json
index b6d12a0..5e69fa9 100644
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@mermkit/cli",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "repository": {
     "type": "git",
     "url": "https://github.com/MermaidKit/mermkit.git"
@@ -19,8 +19,8 @@
     "build": "tsc -b"
   },
   "dependencies": {
-    "@mermkit/core": "0.2.3",
-    "@mermkit/render": "0.2.3",
-    "@mermkit/adapters": "0.2.3"
+    "@mermkit/core": "0.2.4",
+    "@mermkit/render": "0.2.4",
+    "@mermkit/adapters": "0.2.4"
   }
 }
diff --git a/packages/cli/src/cli.ts b/packages/cli/src/cli.ts
index 53b10c9..ba4b72c 100644
--- a/packages/cli/src/cli.ts
+++ b/packages/cli/src/cli.ts
@@ -842,7 +842,9 @@ async function cmdMcp(): Promise<void> {
     if (request.method === "tools/call") {
       const params = request.params ?? {};
       const toolName = resolveMcpToolName((params as { name?: unknown }).name);
-      const toolInput = (params.input ?? {}) as Record<string, unknown>;
+      const toolInput = ((params as { input?: unknown; arguments?: unknown }).input ??
+        (params as { arguments?: unknown }).arguments ??
+        {}) as Record<string, unknown>;
 
       try {
         if (!toolName) {
@@ -871,7 +873,10 @@ async function cmdMcp(): Promise<void> {
 
 async function executeMcpTool(name: string, input: Record<string, unknown>): Promise<Array<{ type: string; [key: string]: unknown }>> {
   if (name === "mermkit.render") {
-    const source = input.diagram as string;
+    if (typeof input.diagram !== "string") {
+      throw new Error("diagram is required and must be a string");
+    }
+    const source = input.diagram;
     const options = (input.options ?? {}) as Record<string, unknown>;
     const diagram = { id: "diagram-1", source: normalizeDiagram(source) };
     const result = await render(diagram, {
@@ -885,18 +890,24 @@ async function executeMcpTool(name: string, input: Record<string, unknown>): Pro
     if (format === "ascii") {
       return [{ type: "text", text: new TextDecoder().decode(result.bytes) }];
     }
-    const mediaType = result.mime;
-    return [{ type: "image", source: { type: "base64", mediaType, data: Buffer.from(result.bytes).toString("base64") } }];
+    const mimeType = result.mime ?? "application/octet-stream";
+    return [{ type: "image", data: Buffer.from(result.bytes).toString("base64"), mimeType }];
   }
 
   if (name === "mermkit.renderBatch") {
-    const diagrams = input.diagrams as Array<{ id?: string; source: string }>;
+    if (!Array.isArray(input.diagrams)) {
+      throw new Error("diagrams is required and must be an array");
+    }
+    const diagrams = input.diagrams as Array<{ id?: string; source?: string }>;
     const options = (input.options ?? {}) as Record<string, unknown>;
     const results: Array<{ type: string; [key: string]: unknown }> = [];
     for (let i = 0; i < diagrams.length; i++) {
       const item = diagrams[i];
       const diagramId = item.id ?? `diagram-${i + 1}`;
       try {
+        if (typeof item.source !== "string") {
+          throw new Error("diagram source must be a string");
+        }
         const diagram = { id: diagramId, source: normalizeDiagram(item.source) };
         const result = await render(diagram, {
           format: (options.format as "svg" | "png" | "pdf" | "ascii") ?? "svg",
@@ -909,7 +920,8 @@ async function executeMcpTool(name: string, input: Record<string, unknown>): Pro
         if (format === "ascii") {
           results.push({ type: "text", text: `[${diagramId}]\n${new TextDecoder().decode(result.bytes)}` });
         } else {
-          results.push({ type: "image", source: { type: "base64", mediaType: result.mime, data: Buffer.from(result.bytes).toString("base64") } });
+          const mimeType = result.mime ?? "application/octet-stream";
+          results.push({ type: "image", data: Buffer.from(result.bytes).toString("base64"), mimeType });
         }
       } catch (error) {
         results.push({ type: "text", text: `[${diagramId}] error: ${errorMessage(error)}` });
@@ -919,14 +931,20 @@ async function executeMcpTool(name: string, input: Record<string, unknown>): Pro
   }
 
   if (name === "mermkit.extract") {
-    const markdown = input.markdown as string;
+    if (typeof input.markdown !== "string") {
+      throw new Error("markdown is required and must be a string");
+    }
+    const markdown = input.markdown;
     const diagrams = extractDiagrams(markdown);
     const text = diagrams.map((d) => `[${d.id}]\n${d.source}`).join("\n\n");
     return [{ type: "text", text: text || "no diagrams found" }];
   }
 
   if (name === "mermkit.term") {
-    const source = input.diagram as string;
+    if (typeof input.diagram !== "string") {
+      throw new Error("diagram is required and must be a string");
+    }
+    const source = input.diagram;
     const diagram = { id: "diagram-1", source: normalizeDiagram(source) };
     const result = await renderForTerminal(diagram, detectCapabilities());
     return [{ type: "text", text: result.text ?? "unable to render for terminal" }];
diff --git a/packages/core/package.json b/packages/core/package.json
index 195b4b5..d47c4df 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@mermkit/core",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "repository": {
     "type": "git",
     "url": "https://github.com/MermaidKit/mermkit.git"
diff --git a/packages/render/package.json b/packages/render/package.json
index 499fb55..75a05be 100644
--- a/packages/render/package.json
+++ b/packages/render/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@mermkit/render",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "repository": {
     "type": "git",
     "url": "https://github.com/MermaidKit/mermkit.git"
@@ -18,7 +18,7 @@
     "build": "tsc -b"
   },
   "dependencies": {
-    "@mermkit/core": "0.2.3"
+    "@mermkit/core": "0.2.4"
   },
   "optionalDependencies": {
     "dompurify": "^3.1.5",