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MCP for data tools (Postgres, BigQuery, S3)

Database and storage MCP servers turn AI assistants into data analysts. Read-only is the default.

Yash ShahMarch 30, 20262 min read

Database MCP servers let AI assistants query the team's data warehouse. Done well, the team's AI becomes a competent analyst. Done badly, the AI starts dropping tables.

Read-only is the default for data tools. Write access is explicit, scoped, audited.

The data integration

A typical data MCP server exposes:

  • list_tables(schema?)
  • describe_table(table_name)
  • run_query(sql) (read-only)
  • sample_table(table_name, limit=10)

The AI can explore and query. It can't modify.

Reviewer ritual

PR review:

  • Read-only by default.
  • Write access (if any) requires explicit role.
  • Query timeout enforced.
  • Audit log for every query.

A real server

A team's Postgres MCP server for analytics:

  • Read-only connection.
  • Query timeout: 30 seconds.
  • Result-size cap: 10,000 rows.
  • Audit log to a separate table.

The AI runs queries. The team reviews the queries via audit. Slow queries are caught.

Trade-offs

  • Read-only safe; less capable.
  • Read-write more capable; more risk.

For analytics, read-only is enough.

Limits

  • Some queries are inherently slow; the AI may need guidance.
  • Some data is sensitive; access controls must be tight.
  • Some tables are large; sampling matters.

What we won't ship

Database MCP servers with broad write access.

Servers without query timeouts.

Servers without per-user query limits.

Servers without audit logging.

Close

MCP for data tools turns AI assistants into analysts. Read-only by default. Audited. Bounded. The team's data is accessible without being at risk.

Related reading


We build AI-enabled software and help businesses put AI to work. If you're shipping data MCP, we'd love to hear about it. Get in touch.

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MCPData ToolsEngineeringDatabaseSQL
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