https://github.com/portofcontext/pctx
pctx is the execution layer for agentic tool calls. It exposes custom tools and MCP servers as code that runs in secure sandboxes for token-efficient calls.
https://github.com/portofcontext/pctx
ai-agents api infrastructure local-development mcp mcp-server open-source
Last synced: 11 days ago
JSON representation
pctx is the execution layer for agentic tool calls. It exposes custom tools and MCP servers as code that runs in secure sandboxes for token-efficient calls.
- Host: GitHub
- URL: https://github.com/portofcontext/pctx
- Owner: portofcontext
- License: mit
- Created: 2025-11-04T16:54:23.000Z (3 months ago)
- Default Branch: main
- Last Pushed: 2026-01-12T21:40:42.000Z (18 days ago)
- Last Synced: 2026-01-13T01:24:41.966Z (18 days ago)
- Topics: ai-agents, api, infrastructure, local-development, mcp, mcp-server, open-source
- Language: Rust
- Homepage: https://portofcontext.com
- Size: 20.9 MB
- Stars: 171
- Watchers: 0
- Forks: 21
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
Awesome Lists containing this project
README
pctx
[](https://portofcontext.com)
[](https://www.npmjs.com/package/@portofcontext/pctx)
[](https://www.rust-lang.org)
[](https://pctx.readthedocs.io/en/latest/)
The open source framework to connect AI agents to tools and mcp with [Code Mode](#what-is-code-mode)
## Install
```bash
# Homebrew
brew install portofcontext/tap/pctx
# cURL
curl --proto '=https' --tlsv1.2 -LsSf https://raw.githubusercontent.com/portofcontext/pctx/main/install.sh | sh
# npm
npm i -g @portofcontext/pctx
```
## Core Functionality
pctx can be run as a stateless HTTP server for Code Mode sessions or as a unified MCP server that exposes Code Mode functionality for registered upstream MCP servers.
```bash
# Start Code Mode for Python SDK
pctx start
# Start Code Mode as a unified MCP server
pctx mcp init
pctx mcp dev
```
## Python SDK
Use the Python SDK if building agents in Python and want to run Code Mode with custom tools and/or MCP servers. The Python SDK is an HTTP client to the `pctx` server.
```bash
pip install pctx-client
```
```python
from pctx_client import Pctx, tool
from agents import Agent # Use any Agent SDK
from agents.run import Runner # This example is OpenAI Agents SDK
@tool
def get_weather(city: str) -> str:
"""Get weather information for a given city."""
return f"It's always sunny in {city}!"
pctx = Pctx(tools=[get_weather]) # or with mcp: servers=[your_mcp]
tools = pctx.openai_agents_tools() # Run Code Mode with any Agent SDK
agent = Agent(
name="GreatCoder",
model="litellm/openrouter/openai/gpt-oss-120b",
instructions="You run code to complete complex tasks.",
tools=tools,
)
```
### Links
- [Python SDK Quickstart and Docs](./pctx-py/README.md)
- [Python API Reference](https://pctx.readthedocs.io/en/latest/)
## Node SDK
Coming soon
## Unified MCP
Use the unified MCP to run Code Mode with MCP servers and want to persist the authentication connections and you do not need to use agent tools (non-mcp tools).
```bash
# Initialize config for upstream mcp connections
pctx mcp init
# Add HTTP or stdio MCP servers
pctx mcp add stripe https://mcp.stripe.com
pctx mcp add memory --command "npx -y @modelcontextprotocol/server-memory"
# Start as HTTP server (dev mode with UI)
pctx mcp dev
# Or start as stdio MCP server
pctx mcp start --stdio
```
For complete CLI documentation, see [CLI.md](docs/CLI.md).
For configuration options, see [Configuration Guide](docs/config.md).
## What is pctx?
`pctx` sits between AI agents and MCP servers. It aggregates multiple upstream MCP servers, handles authentication, and exposes tools through a unified [Code Mode](#what-is-code-mode) interface. Instead of agents managing connections to individual MCP servers, they connect once to pctx.
## What is Code Mode?
Code mode replaces sequential tool calling with code execution. Rather than an agent calling tools one at a time and passing results through its context window, it writes code that executes in a sandbox. Read Anthropic's overview [here](https://www.anthropic.com/engineering/code-execution-with-mcp).
**Traditional MCP flow**:
1. Agent calls `getSheet(id)`
2. Server returns 1000 rows → agent's context
3. Agent calls `filterRows(criteria)`
4. Server returns 50 rows → agent's context
**With Code Mode**:
```typescript
const sheet = await gdrive.getSheet({ sheetId: "abc" });
const orders = sheet.filter((row) => row.status === "pending");
console.log(`Found ${orders.length} orders`);
```
**Result:** 98.7% reduction in tokens (150k → 2k) for this multi-step operation.
## Features
- **Code Mode interface**: Tools exposed as code functions for efficient agent interaction. See [Code Mode Guide](docs/code-mode.md).
- **Upstream MCP server aggregation**: Connect to multiple MCP servers through a single interface. See [Upstream MCP Servers Guide](docs/upstream-mcp-servers.md).
- **Simple config with CLI**: Create the pctx.json config with a simple CLI. pctx.json manages auth, upstream MCPs, logging, and more. See [Config Guide](docs/config.md).
- **Secure authentication**: Source secrets from environment variables, system keychain, and external commands. See [Authentication Section](docs/config.md#authentication) in the CLI configuration docs for more details.
## Security
- LLM generated code runs in an isolated [Deno](https://deno.com) sandbox that can only access the network hosts specified in the configuration file.
- No filesystem, environment, network (beyond allowed hosts), or system access.
- MCP clients are authenticated in pctx. LLMs can never see your auth.
## Update
Depending on the installation method (Homebrew/npm/cURL) the update method is different. Run `which pctx` if you are unsure what you used to install it.
```bash
# Homebrew update
brew upgrade pctx
# cURL update
pctx-update
# npm update
npm upgrade -g @portofcontext/pctx
```
## Develop
- For core dev: install rust and jump into `crates/`
- Client SDK dev: find the README in the SDK
## Learn More
- [Model Context Protocol (MCP)](https://modelcontextprotocol.io/)
- [Code execution with MCP by Anthropic](https://www.anthropic.com/engineering/code-execution-with-mcp)
- [Code Mode explanation by Cloudflare](https://blog.cloudflare.com/code-mode/)