yahoo-finance-mcp

A remote MCP server that exposes Yahoo Finance data (via yfinance) to MCP clients such as Claude (claude.ai, Claude Desktop, Claude Code), ChatGPT connectors, and Notion custom agents.

• 24 tools covering quotes, price history, fundamentals, analyst data, holders, options, funds, screeners, sectors, market summaries, calendars, and live ticks

• Streamable HTTP transport, stateless (scales to zero on Cloud Run)

• OAuth 2.1 with a single pre-registered client (client_id / client_secret), plus Basic auth and client credentials for non-OAuth clients

• One-command deploy to Google Cloud Run with the secret kept in Secret Manager

Tools

Ticker examples: AAPL, 7203.T (Tokyo), ^N225, ^GSPC, USDJPY=X, CL=F, BTC-USD.

Data quality notes

• Previous close. Change and change % are computed from Yahoo's chart metadata (previousClose), not from fast_info.previousClose, which is often off by a day.

• Market summary. yfinance.Market.summary keys results by exchange code, so items on the same exchange overwrite each other (e.g. only 1 of 6 currencies survives). This server calls the same Yahoo endpoint directly and keeps every item.

• Response size. Option chains are trimmed to strikes near the spot price. Price history drops all-zero dividend/split columns and rounds prices. Long lists are capped and report truncated.

• Errors. Every tool returns a readable message to the client, e.g. "symbol not found, use search_symbols" or the list of valid expirations. MCP SDK 2.x would otherwise hide the cause.

Yahoo Finance features intentionally not exposed

Data that Yahoo Finance does not provide (for example Japanese government bond yields) is out of scope.

Related MCP server: Financial Modeling Prep MCP Server

Authentication

Only one pre-registered client is accepted. It is configured with OAUTH_CLIENT_ID and OAUTH_CLIENT_SECRET. Dynamic client registration is disabled.

Design notes:

• Stateless tokens. Tokens are HS256-signed JWTs, so the server keeps no state and works across multiple instances.

• Revocation. Rotating OAUTH_CLIENT_SECRET invalidates every issued token and API key, unless you set OAUTH_SIGNING_KEY separately.

• No consent screen. The authorization endpoint issues a code without asking. That is safe here because exchanging the code requires both the client secret and the PKCE verifier.

• Allowed redirect URIs. Claude (https://claude.ai/api/mcp/auth_callback, https://claude.com/api/mcp/auth_callback), Notion (https://app.notion.com/workflows/mcp/oauth/callback), ChatGPT (https://chatgpt.com/connector_platform_oauth_redirect), and loopback addresses (http://localhost:*, http://127.0.0.1:*). Add more with OAUTH_REDIRECT_URIS (comma-separated).

• Discovery. Metadata is served at /.well-known/oauth-protected-resource (RFC 9728) and /.well-known/oauth-authorization-server (RFC 8414). A 401 response includes WWW-Authenticate: Bearer resource_metadata=....

Configuration

See .env.example. Keep real values in .env, which is excluded by .gitignore, .dockerignore, and .gcloudignore.

Quick start (local)

Requires Python 3.12+ and uv.

cp .env.example .env
# set OAUTH_CLIENT_SECRET in .env, e.g. with: openssl rand -hex 32
set -a; . ./.env; set +a
uv run python server.py          # MCP endpoint: http://localhost:8080/mcp

Try it with curl:

TOKEN=$(curl -s -u "$OAUTH_CLIENT_ID:$OAUTH_CLIENT_SECRET" -d grant_type=client_credentials \
  http://localhost:8080/token | jq -r .access_token)

curl -s http://localhost:8080/mcp \
  -H "Authorization: Bearer $TOKEN" \
  -H 'Content-Type: application/json' -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"get_quote","arguments":{"symbol":"AAPL"}}}'

Tests

uv run pytest              # offline: tools with a stubbed yfinance, auth flows, HTTP transport
uv run pytest -m live      # smoke tests against the real Yahoo Finance API

The offline suite includes an end-to-end OAuth test using the MCP Python SDK's own OAuth client: discovery, authorization, token exchange, and tool calls.

Deploy to Google Cloud Run

Requires the gcloud CLI, logged in to a project with billing enabled.

./deploy.sh
# Override defaults with environment variables:
#   PROJECT (gcloud's current project), REGION (asia-northeast1), SERVICE (yahoo-finance-mcp),
#   CLIENT_ID (yahoo-finance-mcp), SECRET (yahoo-finance-mcp-client-secret), SA_NAME (yahoo-finance-mcp)

The script does the following:

1. Enables the required APIs: Run, Cloud Build, Artifact Registry, Secret Manager, and IAM.

2. Creates a dedicated runtime service account that can read only this one secret.

3. Generates a client secret in Secret Manager on the first run. The value is never printed or written to disk.

4. Builds the container from source and deploys it with min-instances 0, so it costs nothing while idle.

5. Pins PUBLIC_BASE_URL to the deterministic service URL, https://<service>-<project-number>.<region>.run.app.

Read the secret back when you need it for a client:

gcloud secrets versions access latest --secret yahoo-finance-mcp-client-secret

Connecting clients

In the examples below, $URL is your service URL and $SECRET is the client secret.

Claude.ai / Claude Desktop

Settings → Connectors → Add custom connector

• URL: $URL/mcp

• Advanced settings → OAuth Client ID: yahoo-finance-mcp, OAuth Client Secret: $SECRET

Click Connect. The connector becomes available in Claude Desktop and mobile on the same account.

Claude Code

MCP_CLIENT_SECRET=$SECRET claude mcp add --transport http -s user yahoo-finance "$URL/mcp" \
  --client-id yahoo-finance-mcp --client-secret --callback-port 33418
# Then run /mcp in Claude Code → yahoo-finance → Authenticate

Without a browser, use Basic auth instead:

claude mcp add --transport http -s user yahoo-finance "$URL/mcp" \
  --header "Authorization: Basic $(printf 'yahoo-finance-mcp:%s' "$SECRET" | base64)"

Notion custom agents

You need a Business or Enterprise plan. A workspace admin must turn on Enable custom MCP servers under Settings → Connections.

Then open Agent settings → Tools & Access → Add connection → Custom MCP server, and set the URL to $URL/mcp. Pick one of these:

• OAuth (recommended). Authentication = OAuth. Under Advanced settings, set OAuth client ID to yahoo-finance-mcp and OAuth client secret to $SECRET.

• Basic. Username = yahoo-finance-mcp, password = $SECRET.

ChatGPT

Add a custom connector (Settings → Connectors, developer mode) with:

• MCP server URL: $URL/mcp

• Authentication: OAuth, with client ID yahoo-finance-mcp and client secret $SECRET

ChatGPT redirects to https://chatgpt.com/connector_platform_oauth_redirect, which is allowed by default.

Anything else

Any MCP client that supports Streamable HTTP can connect, using either OAuth, Basic auth, or a bearer token from POST /token (see the curl example above).

Rotating the secret

openssl rand -hex 32 | tr -d '\n' | \
  gcloud secrets versions add yahoo-finance-mcp-client-secret --data-file=-
./deploy.sh        # the new revision picks up the new secret; all old tokens become invalid

Then update the secret in every client.

Project layout

server.py        MCP server and the 24 tools
auth.py          OAuth 2.1 authorization server, auth middleware, API key CLI
deploy.sh        Cloud Run deployment
Dockerfile       Container image (uv, Python 3.12, non-root)
tests/           Offline and live test suites
.env.example     Configuration template (no real values)

License

MIT

Acknowledgements

• yfinance by Ran Aroussi and contributors

• MCP Python SDK