| CLICKHOUSE_HOST | Yes | Hostname of the ClickHouse server |
| CLICKHOUSE_USER | Yes | Username for ClickHouse authentication |
| CLICKHOUSE_PASSWORD | No | Password for ClickHouse authentication. Required unless a client certificate uses the default or mutual TLS mode Secret. |
| CLICKHOUSE_PORT | No | ClickHouse HTTP(S) port. Defaults to 8443 when CLICKHOUSE_SECURE=true, 8123 otherwise |
| CLICKHOUSE_SECURE | No | Use HTTPS to connect to ClickHouse |
| CLICKHOUSE_VERIFY | No | Verify SSL certificates |
| CLICKHOUSE_CA_CERT | No | Path to a PEM CA bundle for ClickHouse server certificate verification |
| CLICKHOUSE_CLIENT_CERT | No | Path to a PEM client certificate for the ClickHouse HTTPS connection |
| CLICKHOUSE_CLIENT_CERT_KEY | No | Path to the PEM private key for CLICKHOUSE_CLIENT_CERT |
| CLICKHOUSE_TLS_MODE | No | Client certificate mode: mutual, proxy, or strict |
| CLICKHOUSE_DATABASE | No | Default database to use |
| CLICKHOUSE_ROLE | No | ClickHouse role to activate for the session |
| CLICKHOUSE_ALLOW_WRITE_ACCESS | No | Allow write operations (DDL and DML). Queries run read-only by default |
| CLICKHOUSE_ALLOW_DROP | No | Allow destructive operations (DROP, TRUNCATE, DELETE, UPDATE, REPLACE, CLEAR, and DETACH PERMANENTLY) when write access is also enabled |
| CLICKHOUSE_MCP_QUERY_TIMEOUT | No | Query tool timeout in seconds |
| CLICKHOUSE_MCP_MAX_WORKERS | No | Maximum query worker thread pool size |
| CLICKHOUSE_HOST | Yes | Hostname of the ClickHouse server |
| CLICKHOUSE_USER | Yes | Username for ClickHouse authentication |
| CLICKHOUSE_PASSWORD | No | Password for ClickHouse authentication. Required unless a client certificate uses the default or mutual TLS mode Secret. |
| CLICKHOUSE_PORT | No | ClickHouse HTTP(S) port. Defaults to 8443 when CLICKHOUSE_SECURE=true, 8123 otherwise |
| CLICKHOUSE_SECURE | No | Use HTTPS to connect to ClickHouse |
| CLICKHOUSE_VERIFY | No | Verify SSL certificates |
| CLICKHOUSE_CA_CERT | No | Path to a PEM CA bundle for ClickHouse server certificate verification |
| CLICKHOUSE_CLIENT_CERT | No | Path to a PEM client certificate for the ClickHouse HTTPS connection |
| CLICKHOUSE_CLIENT_CERT_KEY | No | Path to the PEM private key for CLICKHOUSE_CLIENT_CERT |
| CLICKHOUSE_TLS_MODE | No | Client certificate mode: mutual, proxy, or strict |
| CLICKHOUSE_DATABASE | No | Default database to use |
| CLICKHOUSE_ROLE | No | ClickHouse role to activate for the session |
| CLICKHOUSE_ALLOW_WRITE_ACCESS | No | Allow write operations (DDL and DML). Queries run read-only by default |
| CLICKHOUSE_ALLOW_DROP | No | Allow destructive operations (DROP, TRUNCATE, DELETE, UPDATE, REPLACE, CLEAR, and DETACH PERMANENTLY) when write access is also enabled |
| CLICKHOUSE_MCP_QUERY_TIMEOUT | No | Query tool timeout in seconds |
| CLICKHOUSE_MCP_MAX_WORKERS | No | Maximum query worker thread pool size |