ClickHouse MCP Server vs Snowflake-managed MCP server

ClickHouse MCP Server

Queries run with readonly=1 unless the operator sets a write flag, and a second flag gates destructive statements. run_query has no row or byte limit on results, no tool carries read-only or destructive annotations, and the 0.3.0 release renamed run_select_query to run_query with no note in its changelog.

Snowflake-managed MCP server

Tools are governed by Snowflake roles, the SQL tool is read-only by default, and sign-in runs through Snowflake OAuth or a company identity provider. No rate limits or tool-call error codes were found in the reviewed documentation, and a person must create the account, the server object and the OAuth integration before an agent can connect.

ClickHouse MCP Server

1. Put a LIMIT on every run_query call. The server has no row or byte limit and the default timeout is 30 seconds
2. Call the tool run_query. ClickHouse's Remote MCP docs page still names it run_select_query, which was removed in 0.3.0
3. Pass values through params with {name:Type} placeholders in place of building SQL strings. Tuple and Map types can't be bound
4. Set include_detailed_columns to false on list_tables for wide schemas. Page tokens are single-use and expire after one hour
5. Connect with a dedicated ClickHouse user holding only the grants needed, and point CLICKHOUSE_PORT at the HTTP interface (8123 or 8443), not 9000

Snowflake-managed MCP server

1. Send Accept: application/json, text/event-stream and read tools/call results as an SSE stream that ends with data: [DONE]
2. Write the account hostname with hyphens, not underscores, or some clients fail to connect
3. Check the user's DEFAULT_ROLE and DEFAULT_WAREHOUSE first. Clients that request session:role:all get the default role, and a missing warehouse stops the session starting
4. Keep SQL results narrow. Responses over 250 KB are truncated with no paging, and agent tool responses can pass 200 KB
5. Treat invalid_client from /oauth/token-request as a possible network policy block as well as a wrong credential