OAuthProvider

Tool-level OAuth 2.0 Authorization Code flow via MCP elicitation.

OAuthProvider

OAuthProvider(
    name: str,
    build_auth_url: Callable[[str, str], str],
    exchange_code: Callable[
        ..., Coroutine[Any, Any, ExchangeResult]
    ],
    redirect_uri: str,
    user_context: ContextVar[dict | None],
    token_store: TokenStore | None = None,
    pending_store: PendingStore | None = None,
    refresh_token_fn: Callable[
        ..., Coroutine[Any, Any, ExchangeResult]
    ]
    | None = None,
    token_timeout: float = 120.0,
)

Generic MCP OAuth elicitation provider (MCP spec 2025-11-25).

Gates MCP tools behind a third-party OAuth flow. Handles the complete token lifecycle: first-time elicitation, expiry checking, silent refresh, and reactive invalidation.

Token lifecycle

1. First call — no token → URL mode elicitation → browser OAuth → callback → token stored → tool proceeds.
2. Next calls — token valid → tool proceeds immediately.
3. Expiry known (expires_in provided) — silent refresh via refresh_token_fn if available; else re-elicitation.
4. Revocation — tool detects API 401, calls await provider.invalidate_token(sub) and returns an error string → next call triggers re-elicitation.

Elicitation modes

require_token(fail_fast=False) [default] Calls ctx.elicit_url(); the tool call stays open and waits for the OAuth callback via PendingStore. After the callback fires, send_elicit_complete notifies the client (spec §3.4).

require_token(fail_fast=True) Raises UrlElicitationRequiredError (JSON-RPC -32042, spec §3.5) immediately. The client retries the tool call after the OAuth flow.

Parameters:

Name	Type	Description	Default
name	str		required
build_auth_url	Callable[[str, str], str]		required
exchange_code	Callable[..., Coroutine[Any, Any, ExchangeResult]]		required
redirect_uri	str		required
user_context	ContextVar[dict | None]		required
token_store	TokenStore | None	built by ``create_stores()`` from current env vars.	None
pending_store	PendingStore | None	to the store built by ``create_stores()`` from env vars.	None
refresh_token_fn	Callable[..., Coroutine[Any, Any, ExchangeResult]] | None		None
token_timeout	float		120.0

Initialise the provider; see class docstring for parameter descriptions.

Source code in mcpauthkit/providers/oauth_provider.py

def __init__(
    self,
    name: str,
    build_auth_url: Callable[[str, str], str],
    exchange_code: Callable[..., Coroutine[Any, Any, ExchangeResult]],
    redirect_uri: str,
    user_context: ContextVar[dict | None],
    token_store: TokenStore | None = None,
    pending_store: PendingStore | None = None,
    refresh_token_fn: Callable[..., Coroutine[Any, Any, ExchangeResult]] | None = None,
    token_timeout: float = 120.0,
) -> None:
    """Initialise the provider; see class docstring for parameter descriptions."""
    self.name = name
    self.callback_path = urlparse(redirect_uri).path

    self._build_auth_url = build_auth_url
    self._exchange_code = exchange_code
    self._redirect_uri = redirect_uri
    self._user_context = user_context
    self._refresh_token_fn = refresh_token_fn
    self._token_timeout = token_timeout

    # Stores — lazy-init from env vars if not injected
    if token_store is not None and pending_store is not None:
        self._token_store: TokenStore = token_store
        self._pending_store: PendingStore = pending_store
    else:
        from ..store.factory import create_stores

        ts, ps = create_stores(namespace=name)
        self._token_store = token_store if token_store is not None else ts
        self._pending_store = pending_store if pending_store is not None else ps

    # In-process only: state → {session, elicitation_id}
    # Never serialised — used to call send_elicit_complete on the right instance.
    self._sessions: dict[str, dict[str, Any]] = {}

    # Per-request token accessor (set by @require_token decorator)
    self._current_token: ContextVar[str | None] = ContextVar(
        f"elicit_oauth_{name}_token", default=None
    )

from_standard_oauth2 classmethod

from_standard_oauth2(
    *,
    name: str,
    authorization_url: str,
    token_url: str,
    client_id: str,
    client_secret: str,
    scope: str,
    redirect_uri: str,
    user_context: ContextVar[dict | None],
    token_store: TokenStore | None = None,
    pending_store: PendingStore | None = None,
    refresh_token_fn: Callable[
        ..., Coroutine[Any, Any, ExchangeResult]
    ]
    | None = None,
    token_timeout: float = 120.0,
    http_verify: bool | SSLContext | str = True,
) -> OAuthProvider

Convenience factory for any standard OAuth2 Authorization Code provider (GitHub, Google, Jira, Entra, etc.).

Builds build_auth_url and exchange_code internally from standard OAuth2 endpoints so the caller only needs to supply configuration::

github = OAuthProvider.from_standard_oauth2(
    name="github",
    authorization_url="https://github.com/login/oauth/authorize",
    token_url="https://github.com/login/oauth/access_token",
    client_id=settings.github_client_id,
    client_secret=settings.github_client_secret,
    scope="read:user repo",
    redirect_uri="http://localhost:8005/github/callback",
    user_context=current_user,
    http_verify=_SSL_CTX,
)

Parameters:

Name	Type	Description	Default
authorization_url	str	Full URL of the provider's authorization endpoint.	required
token_url	str	Full URL of the provider's token endpoint.	required
client_id	str	OAuth2 client ID.	required
client_secret	str	OAuth2 client secret.	required
scope	str	Space-separated scope string.	required
http_verify	bool | SSLContext | str	Passed as verify= to httpx for the token exchange request.	True
token_store	TokenStore | None	Optional persistent store override.	None
pending_store	PendingStore | None	Optional pending store override.	None
name	str	Same as OAuthProvider.__init__.	required
redirect_uri	str	Same as OAuthProvider.__init__.	required
user_context	str	Same as OAuthProvider.__init__.	required
refresh_token_fn	str	Same as OAuthProvider.__init__.	required
token_timeout	str	Same as OAuthProvider.__init__.	required

Source code in mcpauthkit/providers/oauth_provider.py

@classmethod
def from_standard_oauth2(
    cls,
    *,
    name: str,
    authorization_url: str,
    token_url: str,
    client_id: str,
    client_secret: str,
    scope: str,
    redirect_uri: str,
    user_context: ContextVar[dict | None],
    token_store: TokenStore | None = None,
    pending_store: PendingStore | None = None,
    refresh_token_fn: Callable[..., Coroutine[Any, Any, ExchangeResult]] | None = None,
    token_timeout: float = 120.0,
    http_verify: bool | ssl.SSLContext | str = True,
) -> OAuthProvider:
    """
    Convenience factory for any standard OAuth2 Authorization Code provider
    (GitHub, Google, Jira, Entra, etc.).

    Builds ``build_auth_url`` and ``exchange_code`` internally from standard
    OAuth2 endpoints so the caller only needs to supply configuration::

        github = OAuthProvider.from_standard_oauth2(
            name="github",
            authorization_url="https://github.com/login/oauth/authorize",
            token_url="https://github.com/login/oauth/access_token",
            client_id=settings.github_client_id,
            client_secret=settings.github_client_secret,
            scope="read:user repo",
            redirect_uri="http://localhost:8005/github/callback",
            user_context=current_user,
            http_verify=_SSL_CTX,
        )

    Parameters
    ----------
    authorization_url
        Full URL of the provider's authorization endpoint.
    token_url
        Full URL of the provider's token endpoint.
    client_id
        OAuth2 client ID.
    client_secret
        OAuth2 client secret.
    scope
        Space-separated scope string.
    http_verify
        Passed as ``verify=`` to httpx for the token exchange request.
    token_store
        Optional persistent store override.
    pending_store
        Optional pending store override.
    name, redirect_uri, user_context, refresh_token_fn, token_timeout
        Same as ``OAuthProvider.__init__``.
    """

    def _build_auth_url(state: str, redir: str) -> str:
        return (
            authorization_url
            + "?"
            + urlencode(
                {
                    "client_id": client_id,
                    "redirect_uri": redir,
                    "scope": scope,
                    "state": state,
                    "response_type": "code",
                }
            )
        )

    async def _exchange_code(code: str, state: str, redir: str) -> ExchangeResult:
        async with httpx.AsyncClient(
            timeout=15, follow_redirects=False, verify=http_verify
        ) as client:
            resp = await client.post(
                token_url,
                data={
                    "client_id": client_id,
                    "client_secret": client_secret,
                    "code": code,
                    "redirect_uri": redir,
                    "grant_type": "authorization_code",
                },
                headers={"Accept": "application/json"},
            )
        if resp.status_code != 200:
            logger.error(
                "%s token exchange failed HTTP %s: %s",
                name,
                resp.status_code,
                resp.text[:300],
            )
            return None
        data = resp.json()
        if not data.get("access_token"):
            logger.error("%s token exchange: no access_token in response: %s", name, data)
            return None
        return cast(dict[str, Any], data)

    return cls(
        name=name,
        build_auth_url=_build_auth_url,
        exchange_code=_exchange_code,
        redirect_uri=redirect_uri,
        user_context=user_context,
        token_store=token_store,
        pending_store=pending_store,
        refresh_token_fn=refresh_token_fn,
        token_timeout=token_timeout,
    )

get_token

get_token() -> str | None

Return the access token for the current tool invocation. Only meaningful inside a @require_token()-decorated function.

Source code in mcpauthkit/providers/oauth_provider.py

def get_token(self) -> str | None:
    """Return the access token for the current tool invocation.
    Only meaningful inside a @require_token()-decorated function."""
    return self._current_token.get()

invalidate_token async

invalidate_token(sub: str) -> None

Remove the cached token for a user, forcing re-elicitation on the next tool invocation.

Call this when the downstream API returns 401::

token = provider.get_token()
resp = await _api_get("/path", token)
if resp.status_code == 401:
    await provider.invalidate_token(current_user.get()["sub"])
    return "Authorization expired — please retry."

Source code in mcpauthkit/providers/oauth_provider.py

async def invalidate_token(self, sub: str) -> None:
    """
    Remove the cached token for a user, forcing re-elicitation on the
    next tool invocation.

    Call this when the downstream API returns 401::

        token = provider.get_token()
        resp = await _api_get("/path", token)
        if resp.status_code == 401:
            await provider.invalidate_token(current_user.get()["sub"])
            return "Authorization expired — please retry."
    """
    await self._token_store.delete(sub)
    logger.info("%s token invalidated for sub='%s'", self.name, sub)

require_token

require_token(*, fail_fast: bool = False) -> Callable

Decorator factory that gates an async MCP tool behind OAuth.

Apply AFTER @mcp.tool()::

@mcp.tool(description="...")
@provider.require_token()
async def my_tool(ctx: Context, arg: str) -> str:
    token = provider.get_token()   # guaranteed non-None here
    ...

Parameters:

Name	Type	Description	Default
fail_fast	bool	False (default): tool call stays open during the OAuth flow. True: raises UrlElicitationRequiredError; client must retry.	False

Source code in mcpauthkit/providers/oauth_provider.py

def require_token(self, *, fail_fast: bool = False) -> Callable:
    """
    Decorator factory that gates an async MCP tool behind OAuth.

    Apply AFTER @mcp.tool()::

        @mcp.tool(description="...")
        @provider.require_token()
        async def my_tool(ctx: Context, arg: str) -> str:
            token = provider.get_token()   # guaranteed non-None here
            ...

    Parameters
    ----------
    fail_fast
        False (default): tool call stays open during the OAuth flow.
        True: raises UrlElicitationRequiredError; client must retry.
    """

    def decorator(func: Callable) -> Callable:
        @functools.wraps(func)
        async def wrapper(ctx: Context, *args: Any, **kwargs: Any) -> Any:
            user = self._user_context.get()
            if user is None:
                return "Error: no authenticated user context."

            sub = user.get("sub", "")
            username = user.get("preferred_username", sub)
            logger.debug("%s require_token: sub=%r fail_fast=%s", self.name, sub, fail_fast)

            if fail_fast:
                token = await self._ensure_token_fail_fast(ctx, sub, username)
            else:
                token = await self._ensure_token_blocking(ctx, sub, username)

            if token is None:
                return (
                    f"{self.name.capitalize()} authorization was cancelled "
                    "or timed out. Please try again."
                )

            reset = self._current_token.set(token)
            try:
                return await func(ctx, *args, **kwargs)
            finally:
                self._current_token.reset(reset)

        return wrapper

    return decorator

register

register(app: FastAPI) -> None

Register the OAuth callback GET route on a FastAPI app.

Call this before mounting the MCP sub-app (app.mount("/", ...)). The callback path must also be in open_paths so the auth middleware does not reject the unauthenticated redirect. Use provider.callback_path to reference the path dynamically.

Source code in mcpauthkit/providers/oauth_provider.py

def register(self, app: FastAPI) -> None:
    """
    Register the OAuth callback GET route on a FastAPI app.

    Call this before mounting the MCP sub-app (app.mount("/", ...)).
    The callback path must also be in open_paths so the auth middleware
    does not reject the unauthenticated redirect.  Use
    ``provider.callback_path`` to reference the path dynamically.
    """
    provider = self

    @app.get(provider.callback_path, include_in_schema=False)
    async def _oauth_callback(
        request: Request,
        code: str | None = None,
        state: str | None = None,
        error: str | None = None,
        error_description: str | None = None,
    ):
        name = provider.name.capitalize()

        if error:
            logger.warning("%s callback error: %s — %s", name, error, error_description)
            await provider._fail_pending(state)
            return HTMLResponse(
                _jinja.get_template("oauth_error.html").render(
                    provider_name=name,
                    error=error,
                    error_description=error_description or "",
                ),
                status_code=400,
            )

        if not code or not state:
            return JSONResponse(status_code=400, content={"error": "invalid_request"})

        sub = await provider._handle_callback(code, state)
        if sub is None:
            return HTMLResponse(
                _jinja.get_template("oauth_error.html").render(
                    provider_name=name,
                    error="Code exchange failed",
                    error_description="Could not exchange the authorization code.",
                ),
                status_code=400,
            )

        return HTMLResponse(
            _jinja.get_template("oauth_success.html").render(
                provider_name=name,
                sub=sub,
            )
        )

---

Helper types

_parse_token_data

_parse_token_data(
    result: ExchangeResult, stored_at: float
) -> TokenData | None

Normalise an exchange_code / refresh_token_fn result into a TokenData entry.

Source code in mcpauthkit/providers/oauth_provider.py

def _parse_token_data(result: ExchangeResult, stored_at: float) -> TokenData | None:
    """Normalise an exchange_code / refresh_token_fn result into a TokenData entry."""
    if result is None:
        return None
    if isinstance(result, str):
        return {"access_token": result, "stored_at": stored_at}
    if isinstance(result, dict):
        access = result.get("access_token")
        if not access:
            return None
        entry: TokenData = {"access_token": access, "stored_at": stored_at}
        if rt := result.get("refresh_token"):
            entry["refresh_token"] = rt
        if ei := result.get("expires_in"):
            entry["expires_at"] = stored_at + float(ei)
        return entry
    return None