MotherDuck DuckDB MCP Server

query

Execute SQL queries against MotherDuck or DuckDB databases directly from your AI assistant or IDE. Analyze data with DuckDB SQL dialect efficiently.

Instructions

Use this to execute a query on the MotherDuck or DuckDB database

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": {
      "query": "<query>"
    },
    "name": "query"
  }
}

Input Schema

Name	Required	Description	Default
`query`	Yes	SQL query to execute that is a dialect of DuckDB SQL

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.8.0Aug 9, 2026

TDQS

A3.5/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states that it executes a query, but does not mention whether the query is read-only, can modify data, what permissions are needed, or how results are returned. Given the open-ended nature of SQL queries, this is a significant gap.

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 a single, front-loaded sentence that directly states the tool's purpose without wasted words. It is concise and easy to parse.

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

Completeness3/5

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

Although the tool is simple and has full schema coverage, the absence of annotations and an output schema means the description should clarify expected behavior (e.g., whether it returns results or supports only SELECT queries). It does not, leaving some ambiguity. However, for a minimal query tool, it provides the core essentials.

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

Parameters3/5

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

The schema description covers 100% of the single parameter ('SQL query to execute that is a dialect of DuckDB SQL'), so the description adds no additional meaning. Baseline 3 is appropriate because the schema already provides sufficient semantic detail for the parameter.

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

Purpose4/5

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

The description clearly states the tool's function: 'Use this to execute a query on the MotherDuck or DuckDB database.' It specifies a verb (execute), a resource (query on a database), and distinguishes it from potential sibling tools, though none are listed.

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?

The description begins with 'Use this to execute a query,' giving explicit guidance on when to invoke the tool. Since there are no sibling tools or alternatives mentioned, it fully covers the main use case, though it does not discuss when not to use it or any prerequisites.

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

Deploy Server

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