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The Model Context Protocol (MCP) is an open standard for connecting AI agents to external tools and data sources. Definable’s MCP module lets you connect to any MCP-compatible server and use its capabilities inside your agents.

What MCP Provides

MCP servers expose three types of capabilities:
CapabilityDescriptionExample
ToolsFunctions the agent can callFile operations, database queries, API calls
ResourcesData the agent can readFiles, configurations, live data feeds
PromptsReusable prompt templatesAnalysis templates, code review prompts

Architecture

Transport Types

Definable supports all three MCP transport types:
TransportProtocolBest For
stdioSubprocess stdin/stdoutLocal CLI tools, npm packages
SSEHTTP + Server-Sent EventsRemote servers, legacy MCP
HTTPStreamable HTTPRemote servers, modern MCP

Quick Example

Connect to a filesystem MCP server and use it in an agent:
from definable.agents import Agent
from definable.mcp import MCPToolkit, MCPConfig, MCPServerConfig
from definable.models import OpenAIChat

config = MCPConfig(servers=[
    MCPServerConfig(
        name="filesystem",
        transport="stdio",
        command="npx",
        args=["-y", "@modelcontextprotocol/server-filesystem", "/tmp"],
    ),
])

async with MCPToolkit(config=config) as toolkit:
    agent = Agent(
        model=OpenAIChat(id="gpt-4o"),
        toolkits=[toolkit],
    )
    output = await agent.arun("List all files in /tmp")
    print(output.content)

Key Components