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Add OUTPUT_FORMAT support (defaults to text, supports json) #6

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00d9f65
Add OUTPUT_FORMAT support (defaults to text, supports json)
sam-at-luther Nov 6, 2025
0d366ef
Fix TypeScript compilation error in gdrive_read_file
sam-at-luther Nov 6, 2025
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35 changes: 33 additions & 2 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -136,11 +136,41 @@ npm run build

## 🔧 Usage

### Output Format

The server supports two output formats controlled by the `OUTPUT_FORMAT` environment variable:

- **`text`** (default): Returns human-readable text responses
- **`json`**: Returns structured JSON responses for programmatic consumption

When `OUTPUT_FORMAT=json`:
- `gdrive_search` returns a JSON object with a `files` array containing file objects with `id`, `name`, `mimeType`, `modifiedTime`, and `size` fields
- `gdrive_read_file` returns a JSON object with `fileId`, `mimeType`, and `content` fields

Example JSON output from `gdrive_search`:
```json
{
"files": [
{
"id": "mock_spreadsheet_123",
"name": "Rent Value Update Report",
"mimeType": "application/vnd.google-apps.spreadsheet",
"modifiedTime": "2024-01-01T00:00:00.000Z",
"size": "1024"
}
],
"total": 1
}
```

### As a Command Line Tool

```bash
# Start the server
# Start the server with default text output
node dist/index.js

# Start the server with JSON output
OUTPUT_FORMAT=json node dist/index.js
```

### Integration with Desktop App
Expand All @@ -155,7 +185,8 @@ Add this configuration to your app's server settings:
"args": ["path/to/gdrive-mcp-server/dist/index.js"],
"env": {
"GOOGLE_APPLICATION_CREDENTIALS": "path/to/gdrive-mcp-server/credentials/gcp-oauth.keys.json",
"MCP_GDRIVE_CREDENTIALS": "path/to/gdrive-mcp-server/credentials/.gdrive-server-credentials.json"
"MCP_GDRIVE_CREDENTIALS": "path/to/gdrive-mcp-server/credentials/.gdrive-server-credentials.json",
"OUTPUT_FORMAT": "json"
}
}
}
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124 changes: 86 additions & 38 deletions index.ts
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Expand Up @@ -17,6 +17,36 @@ import path from "path";

const drive = google.drive("v3");

// Get output format from environment variable (defaults to 'text')
const OUTPUT_FORMAT = process.env.OUTPUT_FORMAT || 'text';

// Helper function to check if JSON output is enabled
function isJsonOutput(): boolean {
return OUTPUT_FORMAT === 'json';
}

// Helper function to create MCP tool response
function createResponse(data: string | object, isError: boolean = false) {
let text: string;

// If data is an object and JSON output is enabled, stringify it
if (typeof data === 'object' && isJsonOutput()) {
text = JSON.stringify(data, null, 2);
} else {
text = String(data);
}

return {
content: [
{
type: "text",
text: text,
},
],
isError: isError,
};
}

const server = new Server(
{
name: "gdrive",
Expand Down Expand Up @@ -181,18 +211,28 @@ server.setRequestHandler(CallToolRequestSchema, async (request) => {
fields: "files(id, name, mimeType, modifiedTime, size)",
});

const fileList = res.data.files
?.map((file: any) => `${file.name} (${file.mimeType}) - ID: ${file.id}`)
const files = res.data.files || [];

// Return JSON format if OUTPUT_FORMAT=json
if (isJsonOutput()) {
const jsonResponse = {
files: files.map((file: any) => ({
id: file.id,
name: file.name,
mimeType: file.mimeType,
modifiedTime: file.modifiedTime,
size: file.size,
})),
total: files.length,
};
return createResponse(jsonResponse, false);
}

// Return text format (default)
const fileList = files
.map((file: any) => `${file.name} (${file.mimeType}) - ID: ${file.id}`)
.join("\n");
return {
content: [
{
type: "text",
text: `Found ${res.data.files?.length ?? 0} files:\n${fileList}`,
},
],
isError: false,
};
return createResponse(`Found ${files.length} files:\n${fileList}`, false);
} catch (error: any) {
// Extract more detailed error information from Google API errors
let errorMessage = error.message || error.toString();
Expand Down Expand Up @@ -235,15 +275,17 @@ server.setRequestHandler(CallToolRequestSchema, async (request) => {
};
process.stderr.write('Google Drive API error: ' + JSON.stringify(errorLog, null, 2) + '\n');

return {
content: [
{
type: "text",
text: `Error searching Google Drive: ${errorMessage}${errorCodeSuffix}`,
},
],
isError: true,
};
// Return JSON format for errors if OUTPUT_FORMAT=json
if (isJsonOutput()) {
const errorResponse = {
error: true,
message: errorMessage,
code: error.code || error.response?.data?.error?.code || 'unknown',
};
return createResponse(errorResponse, true);
}

return createResponse(`Error searching Google Drive: ${errorMessage}${errorCodeSuffix}`, true);
}
} else if (request.params.name === "gdrive_read_file") {
const fileId = request.params.arguments?.file_id as string;
Expand All @@ -253,25 +295,31 @@ server.setRequestHandler(CallToolRequestSchema, async (request) => {

try {
const result = await readFileContent(fileId);
return {
content: [
{
type: "text",
text: result.content,
},
],
isError: false,
};

// Return JSON format if OUTPUT_FORMAT=json
if (isJsonOutput()) {
const jsonResponse = {
fileId: fileId,
mimeType: result.mimeType,
content: result.content,
};
return createResponse(jsonResponse, false);
}

// Return text format (default)
return createResponse(result.content as string, false);
} catch (error: any) {
return {
content: [
{
type: "text",
text: `Error reading file: ${error.message}`,
},
],
isError: true,
};
// Return JSON format for errors if OUTPUT_FORMAT=json
if (isJsonOutput()) {
const errorResponse = {
error: true,
message: error.message || error.toString(),
fileId: fileId,
};
return createResponse(errorResponse, true);
}

return createResponse(`Error reading file: ${error.message}`, true);
}
}
throw new Error("Tool not found");
Expand Down