Universal Database MCP Server

Query

query

Executes SQL statements securely against configured databases, supporting parameterized inputs and blocking destructive operations in read-only mode.

Instructions

Execute a SQL query against the database.

Supports parameterized queries for injection safety. In read-only mode, destructive operations (INSERT, UPDATE, DELETE, DROP, etc.) are blocked.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "sql": "<sql>"
    },
    "name": "query"
  }
}

Input Schema

Name	Required	Description
`sql`	Yes	SQL query to execute
`params`	No	Optional list of parameters for parameterized queries (use instead of string formatting)
`database`	No	Database key (format: "type:name"). Required when multiple databases are configured.

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.1.3Sep 8, 2026

TDQS

A4.2/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are present, so the description carries full responsibility. It discloses read-only mode blocking destructive operations, but does not explain error behavior, side effects, or what happens to the query if parameters are omitted, leaving some ambiguity.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two concise sentences that front-load the core purpose and immediately follow with important usage constraints. No fluff or redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given that an output schema exists, the description does not need to detail return values. It covers the essential inputs and key behavioral constraints, though it could mention potential errors or edge cases for full completeness.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema already defines the parameters, but the description adds meaning by explaining that params are for parameterized queries and database is required when multiple databases are configured. This goes beyond the raw schema definitions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states 'Execute a SQL query against the database' with a clear verb and resource. It is distinct from sibling tools like schema or explain, which serve different purposes.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It provides explicit guidance to use parameterized queries for injection safety and notes that destructive operations are blocked in read-only mode. While not explicitly contrasting with sibling tools, these practical tips help decide how to invoke the tool correctly.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server