Codex is one of the most popular coding harnesses out there. And MCP makes the experience even better. With Blocknative MCP integration, you can draft, triage, summarise emails, and much more, all without leaving the terminal or the app, whichever you prefer.
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Why use Composio?
Apart from a managed and hosted MCP server, you will get:
- CodeAct: A dedicated workbench that allows GPT to write its code to handle complex tool chaining. Reduces to-and-fro with LLMs for frequent tool calling.
- Large tool responses: Handle them to minimise context rot.
- Dynamic just-in-time access to 20,000 tools across 870+ other Apps for cross-app workflows. It loads the tools you need, so GPTs aren't overwhelmed by tools you don't need.
How to install Blocknative MCP in Codex
Run the setup command
Run this command in your terminal to add the Composio MCP server to Codex.
It will initiate the authentication in a browser window, authorize Codex to access your Composio account.
(Optional) Authenticate with OAuth
To authenticate manually, run the login command to open a browser window and authorize Codex to access your Composio account.
Verify the connection
Run codex mcp list to confirm Composio appears as a registered MCP server.
Codex App
Codex App follows the same approach as VS Code.
- Click ⚙️ on the bottom left → MCP Servers → + Add servers → Streamable HTTP:
- Fill the header and Key fields with
{ "x-consumer-api-key" = "ck_*******" }. - The Key is the Composio API key, that you can find on dashboard.composio.dev
- Click on Authenticate and authorize Codex to your Composio account and you're all set.
- Restart and verify if it's there in
.codex/config.toml
What is the Blocknative MCP server, and what's possible with it?
The Blocknative MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Blocknative account. It provides structured and secure access to real-time mempool data and transaction management features across public blockchains, so your agent can monitor transactions, analyze gas prices, configure filters, and manage blockchain event subscriptions on your behalf.
- Real-time mempool monitoring: Instruct your agent to subscribe to Ethereum transaction hashes or addresses and receive instant updates on their status and events.
- Gas price analysis and estimation: Have your agent fetch current gas price distributions, base fee predictions, and inclusion probability estimates to help optimize transaction fees.
- Customizable event filters: Let your agent configure advanced mempool filters and ABI decoding, so you can track only the events or transactions that matter to your workflow.
- Multichain event subscriptions: Enable your agent to subscribe or unsubscribe to transaction and account events across multiple supported blockchains using the Blocknative multichain SDK.
- Supported chain discovery: Ask your agent to list and discover which blockchains and gas oracles are available for monitoring and analytics.
Supported Tools & Triggers
Tools
Conclusion
You've successfully integrated Blocknative with Codex using Composio's MCP server. Now you can interact with Blocknative directly from your terminal, VS Code, or the Codex App using natural language commands.
Key benefits of this setup:
- Seamless integration across CLI, VS Code, and standalone app
- Natural language commands for Blocknative operations
- Managed authentication through Composio
- Access to 20,000+ tools across 870+ apps for cross-app workflows
- CodeAct workbench for complex tool chaining
Next steps:
- Try asking Codex to perform various Blocknative operations
- Explore cross-app workflows by connecting more toolkits
- Build automation scripts that leverage Codex's AI capabilities
How to build Blocknative MCP Agent with another framework
Explore Other Toolkits
FAQ
What are the differences in Tool Router MCP and Blocknative MCP?
With a standalone Blocknative MCP server, the agents and LLMs can only access a fixed set of Blocknative tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Blocknative and many other apps based on the task at hand, all through a single MCP endpoint.
Can I use Tool Router MCP with Codex?
Yes, you can. Codex fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Blocknative tools.
Can I manage the permissions and scopes for Blocknative while using Tool Router?
Yes, absolutely. You can configure which Blocknative scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.
How safe is my data with Composio Tool Router?
All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Blocknative data and credentials are handled as safely as possible.
