hedron-mcp

Deny-by-default MCP Streamable HTTP projection for Hedron.

Disabled and empty until resources and tools are explicitly registered. MCP never grants authority beyond the authenticated principal. Installing the package without registrations remains a no-op empty server.

Also available as the flagship extra hedron[mcp].

Package maturity: Beta (0.2.x) · pin >=0.2.0,<0.3

Production-grade for the declared Supported inventory (phase 0.32 / RFC-0065). Mutating tools remain Experimental (allow_mutations=True).

Install

pip install "hedron-mcp>=0.2.0,<0.3"
# or
uv add "hedron-mcp>=0.2.0,<0.3"
# via flagship:
pip install "hedron[mcp]>=0.32.0,<0.33"

Requires Python 3.11–3.14.

Quick start

from hedron import Hedron
from hedron_mcp import McpProjection, McpResource, McpTool, mount_mcp

app = Hedron(
    title="MCP demo",
    security="standard",
    session_secret="dev-only",
)

# Prefer session / host auth. Header identity is host-owned opt-in only —
# the default resolver never trusts x-hedron-principal / x-user.
projection = McpProjection(
    enabled=True,
    principal_resolver=lambda request: request.session.get("user"),
)
projection.register_resource(McpResource(uri="hedron://page/home", name="home"))
projection.register_tool(
    McpTool(
        name="status",
        schema={"type": "object", "properties": {}},
        mutate=False,
        handler=lambda: {"ok": True},
    )
)
mount_mcp(app, projection)

License

MIT