ChatGPT Developer Mode Integration

January 29, 2026 · View on GitHub

⚠️ Smithery Temporarily Unavailable: Smithery has changed their deployment model to require external hosting. Use the Cloudflare Worker deployment method below for ChatGPT integration.

This guide explains how to expose the Attio MCP server to ChatGPT users in two configurations:

Full Developer Mode – Pro/Plus accounts with the Developer Mode beta enabled can access the entire Attio toolset, including write operations, with built-in approval flows.
Search-Only Compatibility – For accounts without Developer Mode, expose a minimal search/fetch surface that mirrors OpenAI's baseline MCP requirements.

The server now publishes MCP safety annotations (readOnlyHint, destructiveHint, idempotentHint) on every tool definition so ChatGPT can make informed approval decisions.

1. Requirements

Scenario	Requirements
Developer Mode	ChatGPT Pro/Plus subscription, browser access, Settings → Connectors → Advanced → Developer Mode enabled
Search Only	Any ChatGPT account that supports custom connectors

Server prerequisites

Self-hosted Cloudflare Worker deployment (see Cloudflare Worker Guide)
Set ATTIO_API_KEY/ATTIO_WORKSPACE_ID for Attio API access

2. Enabling Developer Mode Access

Prerequisites for ChatGPT Integration

IMPORTANT: ChatGPT Developer Mode requires a publicly accessible HTTPS endpoint with OAuth support. Deploy using the Cloudflare Worker template.

Setup Steps

Deploy the Cloudflare Worker:

cd examples/cloudflare-mcp-server
npm install
wrangler kv:namespace create "TOKEN_STORE"
# Update wrangler.toml with the KV namespace ID
wrangler secret put ATTIO_CLIENT_ID
wrangler secret put ATTIO_CLIENT_SECRET
wrangler secret put TOKEN_ENCRYPTION_KEY
wrangler deploy

See Cloudflare Worker Deployment Guide for detailed instructions.

Expose the full tool catalogue - Do NOT set ATTIO_MCP_TOOL_MODE. The server exposes all tools by default.
Configure ChatGPT:
- Open Settings → Connectors → Advanced.
- Enable Developer Mode.
- Add your Cloudflare Worker URL: https://your-worker.your-subdomain.workers.dev/mcp
- Complete OAuth authorization when prompted
OAuth Authentication:
- ChatGPT will redirect to your Worker for OAuth authorization
- Grant permissions for the Attio MCP server
- The Worker handles token refresh automatically
Verification:
- ChatGPT will automatically auto-approve tools with readOnlyHint: true (e.g. records.search, records.get_details)
- Prompt for approval on write tools (create-record, update-record) and destructive tools (delete-record)

Approval messaging tips

Tool descriptions should clearly explain the effect of the operation (e.g. “Create a new Attio contact”).
Validation errors should mention that approval may be required (we already surface this in handler responses).

3. Search-Only Compatibility Mode

For accounts without Developer Mode, configure ATTIO_MCP_TOOL_MODE: 'search' as an environment variable in your Cloudflare Worker.

When this mode is active, the server will only advertise:

Tool	Behaviour
`search`	Delegates to the universal search service and returns JSON-encoded results in a single text content item
`fetch`	Retrieves the full record payload for a search result ID
`health-check`/`aaa-health-check`	Simple readiness probes

All other tools are filtered out at registry time and ignored by the dispatcher. This is ideal for accounts without Developer Mode or for a constrained roll-out.

Unset the variable (or set it to any value other than search) to restore the full tool catalogue.

4. Testing Matrix

Mode	Suggested Tests
Developer Mode	`npm test -- --run test/services/openai-compatibility.service.test.ts`, plus manual validation in ChatGPT Developer Mode
Search-only	Same test suite plus a quick `list_tools` in ChatGPT to confirm only `search`/`fetch` are visible

Note: Full MCP end-to-end suites still require Attio API credentials. Run them before production rollout (npm test) or rely on CI where the secrets are available.

5. Troubleshooting

Symptom	Likely Cause	Fix
ChatGPT requests consent for read-only tools	`readOnlyHint` missing	Confirm you are running a version that includes safety annotations
ChatGPT only sees 'search' and 'fetch' tools	`ATTIO_MCP_TOOL_MODE` environment variable set	Remove `ATTIO_MCP_TOOL_MODE` - server defaults to full mode
ChatGPT cannot see write tools	Running with `ATTIO_MCP_TOOL_MODE: 'search'`	Remove the environment variable - do NOT set it for full access
ChatGPT cannot connect to server	Worker not deployed or incorrect URL	Verify your Cloudflare Worker is deployed and use the correct `/mcp` endpoint
OAuth authentication fails	Cloudflare Worker OAuth not configured properly	Check ATTIO_CLIENT_ID, ATTIO_CLIENT_SECRET, and TOKEN_ENCRYPTION_KEY secrets
Tools show "unauthorized" errors	API credentials not configured	Configure `ATTIO_API_KEY` and `ATTIO_WORKSPACE_ID` in Cloudflare Worker secrets
`search` returns no results	Ensure Attio API credentials are set and universal search works in Claude/CLI	Verify credentials in Cloudflare Worker configuration
PR validation fails with missing Attio credentials	Expected if secrets are not available locally; see `README.md` testing notes	Use Cloudflare Worker for production deployments with proper credential management

6. Next Steps

Monitor approval logs to verify the safety flow.
Add targeted UI messaging in ChatGPT descriptions for high-risk tools (delete-record, batch-operations).
Expand the test suite with real Developer Mode integration tests once mocked approval APIs become available.