mssql-mcp

A read-only Microsoft SQL Server MCP server using connection details from AWS Secrets Manager at tool-call time — nothing is read from disk or environment variables except the secret reference itself.

This is a light-weight mcp meant for local development use. It avoids database credentials in your agent config, works nicely with a credential process and tools like aws-vault, and allows for readonly database access and schema discovery.

Cross-platform: it's a pure-JavaScript MCP server (no native or ODBC dependencies), so it runs identically on macOS, Linux, and Windows via npx.

Configure in .claude.json

{
  "mcpServers": {
    "my-db": {
      "command": "npx",
      "args": ["-y", "@dhipskind253/mssql-mcp"],
      "env": {
        "AWS_ACCOUNT_ID": "123456789012",
        "SECRET_NAME": "my-aws-secret",
        "AWS_REGION": "us-east-1",
        "TRUST_SERVER_CERTIFICATE": "false"
      }
    }
  }
}

Standard AWS SDK env vars (AWS_PROFILE, AWS_ACCESS_KEY_ID, etc.) are honored via the default credential provider chain. Most users just need aws sso login to be current.

Related MCP server: MSSQL MCP Python Server

Required secret JSON

The secret value must be a JSON document with at least these fields:

{
  "host": "myserver.database.windows.net",
  "port": 1433,
  "database": "mydb",
  "username": "ro_user",
  "password": "..."
}

database may also be supplied as dbname — the field name AWS uses in its built-in RDS-credentials secret template. If both are present, database wins.

Optional fields (with defaults shown):

TLS cert trust is not read from the secret — set TRUST_SERVER_CERTIFICATE in the MCP server's env block instead. Any trustServerCertificate field in the secret JSON is ignored.

Read-only by design

This server cannot insert, update, or delete data. Two layers enforce that:

1. The run_select tool lexically rejects anything that isn't a single SELECT or WITH (CTE) statement — including INSERT, UPDATE, DELETE, EXEC, MERGE, DROP, ALTER, SELECT INTO, etc.

2. No other tool emits write SQL. get_procedure_definition returns procedure source — it does not run procedures.

Courtesy note: treat the lexical check as UX, not a security boundary. As a courtesy to your future self, configure the credentials you put in Secrets Manager to be a read-only database login — one with SELECT and VIEW DEFINITION only. That way an accidental write (or a future bug here) is rejected by SQL Server itself.

Refreshing AWS credentials without restarting

Because the server uses the default AWS credential chain, an expired SSO session can be recovered without restarting Claude or the MCP server:

1. Run aws sso login in any terminal.

2. Ask Claude to call the refresh_secret tool.

3. Continue working.

If a tool call fails because of AWS auth, the error message will tell you exactly that and prompt the same flow. Errors are tagged with stable prefixes:

Tools

Local development

npm install
npm run build
# point your .claude.json command at the local build:
#   "command": "node",
#   "args": ["/absolute/path/to/mssql-mcp/dist/index.js"]