tossinvest-mcp is a Model Context Protocol (MCP) server designed to let users query Korean and U.S. stocks and place orders through a Toss Securities account in MCP-compatible AI clients such as Claude. It uses the Toss Securities Open API, so you must first create and obtain a toss client key (TOSS_CLIENT_ID and TOSS_CLIENT_SECRET) in the Toss Securities Open API developer console.
Main capabilities You can query stock quotes, order books, trades, charts, investor fund flows, positions, orderable amounts, and exchange rates; after going through the user confirmation process, you can register regular orders, as well as SINGLE, OCO, and OTO conditional orders. It is suitable for MCP-compatible AI clients such as Claude Code and Claude Desktop.
How to use After this package is published to npm, there is no need to clone the repository when using Claude Code. Add the corresponding configuration to .mcp.json in the project, obtain TOSS_CLIENT_ID and TOSS_CLIENT_SECRET from the Toss Securities Open API developer console and fill them in, then restart Claude Code. Credentials should not be committed to Git, nor shared in prompts. npx downloads the package on first run, then uses the cache; Node.js 18 or higher is required. When running locally, you can copy .env.example and fill in the credentials. On first run, it downloads the stock master data for KOSPI, KOSDAQ, NASDAQ, NYSE, and AMEX, then uses the cache and updates it once a day in the background.
Order confirmation mechanism Placing an order is always a two-step process. toss_prepare_order or toss_prepare_conditional_order does not execute the order, it only generates a preview. The AI must show the content to the user and only after obtaining explicit confirmation should it call toss_submit_prepared_order. The confirmation token is bound only to that one order, expires after 60 seconds, and becomes invalid after one use or after a server restart. This mechanism is intended to reduce the risk of accidental orders, but it cannot replace the user's final check.
Notes and limitations API's numeric fields are returned as strings, and percentage changes are in decimal form, for example -0.3799 means -37.99%. API limits are: quotes 15 times per second, assets 5 times per second, accounts 1 time per second. This project is unrelated to Toss Securities, is an unofficial tool, does not provide investment advice, and users bear the risk of use themselves.
