Context - Dedalus Docs

The Context object gives you access to request-scoped utilities while a tool/resource/prompt is executing—primarily logging, progress, and request metadata. Use get_context() to fetch the active context. Note: get_context() only works inside an active MCP request handler. Calling it elsewhere raises LookupError.

Get Context

from dedalus_mcp import get_context, tool

@tool(description="Process data with logging")
async def process(data: str) -> str:
    ctx = get_context()
    await ctx.info("Processing", data={"bytes": len(data)})
    return "done"

Auto-injection (tools + dependencies)

In tools (and dependency callables), parameters annotated as Context can be auto-injected by the framework—no need to call get_context() manually:

from dedalus_mcp import Context, tool

@tool(description="Same as process(), but Context is injected")
async def process_injected(data: str, ctx: Context) -> str:
    await ctx.info("Processing", data={"bytes": len(data)})
    return "done"

Available features

Feature	API	What it does
Logging	`ctx.debug()`, `ctx.info()`, `ctx.warning()`, `ctx.error()`, `ctx.log()`	Send log messages to the client
Request metadata	`ctx.request_id`, `ctx.session_id`, `ctx.progress_token`	Identify the current request/session and progress token
Server/runtime access	`ctx.server`, `ctx.runtime`	Access runtime wiring (if present)
Auth context	`ctx.auth_context`	Access the auth context (if authorization is enabled)
Progress	`ctx.report_progress(...)`, `ctx.progress(...)`	Emit progress notifications (if the client provided a progress token)
Dispatch (optional)	`ctx.dispatch(...)`	Send authenticated HTTP requests via the configured dispatch backend (if configured)
Connection resolution (optional)	`ctx.resolve_client(...)`	Resolve a connection handle into a client via the configured resolver (if configured)

Request metadata

from dedalus_mcp import get_context, tool

@tool(description="Show request metadata")
async def my_tool() -> dict:
    ctx = get_context()
    return {
        "request_id": ctx.request_id,
        "session_id": ctx.session_id,          # may be None (e.g. stdio)
        "progress_token": ctx.progress_token,  # may be None if client didn't request progress
    }

Authorization context

If authorization is enabled, ctx.auth_context may be set; otherwise it’s None:

from dedalus_mcp import get_context, tool

@tool(description="Show auth context presence")
async def whoami() -> dict:
    ctx = get_context()
    if ctx.auth_context is None:
        return {"user": "anonymous"}
    return {"auth_context": "present"}

Progress example

import anyio
from dedalus_mcp import get_context, tool

@tool(description="Process files with progress reporting")
async def process_files(paths: list[str]) -> dict:
    ctx = get_context()
    processed = 0
    async with ctx.progress(total=len(paths)) as tracker:
        for _path in paths:
            await anyio.sleep(0.01)
            processed += 1
            await tracker.advance(1)

    return {"processed": processed}

Last modified on June 30, 2026

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