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A Model Context Protocol (MCP) server for Google BigQuery that enables AI agents to interact with BigQuery databases through natural language queries and schema exploration.

This project was developed by Snow Leopard AI as a benchmarking tool for our platform, and we're making it publicly available for the community to use and build upon.

What is MCP?

The Model Context Protocol (MCP) is an open standard that allows AI applications to securely connect to external data sources and tools. This BigQuery MCP server acts as a bridge between AI agents and your BigQuery datasets.

Related MCP server: BigQuery MCP Server

Snow Leopard BigQuery MCP Server Features

Resources

Resource URI

Description

bigquery://tables

List all tables available to the agent

bigquery://tables/{table}/schema

Get the schema of a specific table

Tools

Tool

Description

list_tables(table: str) (optional)

List available tables

get_schema(table: str) (optional)

Get the schema of a given table

query(sql: str)

Execute BigQuery SQL and return results

Quick Start: Claude Desktop

Prerequisites

Before getting started, ensure you have:

1. Setup Google Cloud

First, we need to authenticate with Google.

gcloud auth application-default login

This opens your browser to authenticate your local machine with Google Cloud.

2. Configure Claude Desktop

Edit your claude_desktop_config.json file to add the BigQuery MCP server.

Application: Claude > Settings > Developer > Edit Config
Mac: ~/Library/Application\ Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\\Claude\\claude_desktop_config.json

You will need to set your project to a Google Cloud project with permissions to submit bigquery jobs. If you do not have a project that you can run bigquery jobs on, create and test one by following Google's BigQuery Quickstart Guide Create a project and follow the instructions to query a public dataset.

{
  "mcpServers": {
    "bigquery": {
      "command": "uvx",
      "args": [
        "sl-bigquery-mcp", 
        "--dataset",
        "bigquery-public-data.usa_names",
        "--project",
        "๐Ÿšจ <projectName> ๐Ÿšจ"
      ]
    }
  }
}

3. Close Claude Desktop and Launch it from the terminal

Depending on how you have installed uv, the uvx executable may not be in Claude Desktop's PATH if it is launched from the GUI. To be sure uvx is accessible from Claude Desktop, let's run it in the terminal.

open -a claude

After saving the configuration, restart Claude Desktop. You should now be able to ask Claude questions about your BigQuery data!

Example Query

What are the top 10 most popular names in 2020?

Configuration Options

To see a complete list of parameters:

uvx sl-bigquery-mcp --help
Usage: sl-bigquery-mcp [OPTIONS]

โ•ญโ”€ Options โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ•ฎ
โ”‚ --mode                       [stdio|sse|streamable-http]  MCP transport protocol [default: stdio]                                                     โ”‚
โ”‚ --dataset                    TEXT                         Dataset(s) for mcp resources. Will create resources for all tables.                         โ”‚
โ”‚ --table                      TEXT                         Table(s) for mcp resources. Can be specified as project.dataset.table or dataset.table      โ”‚
โ”‚ --enable-list-tables-tool    --no-enable-list-tables-tool Registers list_resources tool [default: enable-list-tables-tool]                            โ”‚
โ”‚ --enable-schema-tool         --no-enable-schema-tool      Registers get_schema tool [default: enable-schema-tool]                                     โ”‚
โ”‚ --project                    TEXT                         BigQuery project [env var: BQ_PROJECT] [default: None]                                      โ”‚
โ”‚ --api-method                 [INSERT|QUERY]               BigQuery client api_method [default: QUERY]                                                 โ”‚
โ”‚ --port                       INTEGER                      [default: 8000]                                                                             โ”‚
โ•ฐโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ•ฏ

Troubleshooting / FAQ

An MCP Error has occurred

First, check out your Claude Desktop app logs (in the same directory as the config file) for more verbose errors / logging

On Startup

This usually means Claude is having issues starting the mcp server. Frequently this is due to uvx being inaccessible from the application. In this case, use the full path to your uvx executable instead of just uvx in claude_desktop_config.json.

To find your uv executable, run

which uvx

Otherwise, this may be caused by bad arguments, dependency version incompatibilities, or bugs. If you run into the last two, please file an issue describing the problem.

On Resource / Tool Usage

This may be a misconfiguration mcp server, authentication issues, the llm getting too much data, or of course, product bugs. After checking the logs, consider using the MCP Inspector to debug your issue. And of course, file any bugs you find on our issue board.

Local Development & Testing

Setup Development Environment

  1. Clone the repository

  2. Setup virtual environment and install dependencies

  3. Verify installation

git clone https://github.com/SnowLeopard-AI/bigquery-mcp.git
cd bigquery-mcp

uv sync
source .venv/bin/activate

sl-bigquery-mcp --help

Authenticate with Google Cloud

The following command will launch a browser for you to login to your google cloud account. You must have a Google Cloud project with BigQuery enabled. If you don't, see Google's bigquery setup guide.

gcloud auth application-default login
gcloud config set project <projectName>
gcloud auth application-default set-quota-project <projectName>

Running Tests

Run the tests to make sure your dev environment is properly configured.

pytest tests

Note: the tests run actual BigQuery queries against public datasets and require authentication.

Local MCP Inspector

For hands-on testing and development, use the MCP Inspector tool:

npx @modelcontextprotocol/inspector uv run sl-bigquery-mcp --dataset bigquery-public-data.usa_names

Contributing

We welcome contributions! Please coordinate with us on discord to ensure your changes can quicly make it into the repo. Communicating before coding always saves time.

For logistics of contributing to an open source project, see the first contributions repository.

Support

Issues: GitHub Issues
Documentation: BigQuery Documentation
MCP Protocol: Model Context Protocol
Contact: Discord Server

Available Tools

3 tools
get_schemaC

Get the schema for a given table

ParametersJSON Schema
NameRequiredDescriptionDefault
tableYes

TDQS

C2.8/5.0
Behavior2/5

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

No annotations exist, so the description carries the full burden of behavioral disclosure. It implies a read-only operation, but it does not explain what the schema includes, what happens for unknown tables, whether access is required, or what the response format will be.

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

Conciseness4/5

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

The description is a single declarative sentence with no filler, and the core purpose is front-loaded. It is appropriately brief for a simple tool, though the brevity comes at the cost of missing behavioral and parameter context.

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?

For a one-parameter read-only tool, this is minimally viable: it states the operation and target. However, it omits return expectations and useful context such as linking to list_tables for discovering valid table names, leaving notable gaps for an agent to call it confidently.

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

Parameters2/5

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

Schema description coverage is 0%, so the description needed to clarify the 'table' parameter. It only restates the concept of 'a given table' in English and adds no details about valid values, naming conventions, or how to discover available tables.

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 a specific action ('Get') and resource ('the schema for a given table'), which distinguishes it in kind from siblings like query and list_tables. It does not explicitly contrast with siblings, but the resource type is evident enough.

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

Usage Guidelines2/5

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

There is no explicit guidance on when to use this tool versus query or list_tables. The intended use is implied by the tool name and one-line description, but no prerequisites, exclusions, or alternative conditions are provided.

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

list_tablesA

List the tables available

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

TDQS

A3.5/5.0
Behavior2/5

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

With no annotations, the description carries the full burden of behavioral disclosure. It only says 'List the tables available' โ€” no mention of whether system tables are included, the return format, pagination, or authentication requirements. The word 'list' implies read-only, but scope is vague.

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?

A single, front-loaded sentence with no filler. Every word contributes to the purpose, making it appropriately concise for a zero-parameter tool.

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?

For a simple list tool with no parameters or output schema, this is minimally adequate. However, it doesn't clarify what 'available' means (e.g., current schema, user permissions), the return shape, or how it relates to siblings โ€” leaving a small but notable gap.

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 tool has zero parameters, so the schema fully documents the input surface. The description doesn't need to add parameter semantics; baseline of 4 applies.

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 clearly states a specific verb ('List') and resource ('tables'), and the phrase 'available' conveys scope. Even without naming siblings, the operation is obviously distinct from 'query' (data retrieval) and 'get_schema' (schema inspection).

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

Usage Guidelines2/5

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

The description gives no guidance on when to use this tool versus alternatives. There is no mention of prerequisites, whether to call this before query/get_schema, or any context indicating selection criteria.

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

queryC

Executes the provided BigQuery sql statement and returns the results

ParametersJSON Schema
NameRequiredDescriptionDefault
sqlYesBigQuery sql statement to execute

TDQS

C2.9/5.0
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 disclosing behavior. It states that SQL is executed and results are returned, but it does not say whether this is read-only, whether DDL/DML is permitted, whether side effects can occur, or what happens if the query is expensive or large. This is a significant gap for an arbitrary SQL execution tool.

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, direct sentence that front-loads the action and result. There is no wasted wording or redundant detail.

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

Completeness2/5

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

With no annotations and no output schema, the description needs to provide enough context for an agent to invoke the tool safely and correctly. For an arbitrary SQL execution tool, it omits important constraints: whether only SELECT is allowed, how results are returned, row limits, and potential cost or side-effect warnings. The description is minimally functional but not complete for this kind of operation.

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 input schema already documents the single 'sql' parameter with 100% coverage. The description essentially restates the schema field ('BigQuery sql statement'), adding little meaning beyond what the structured definition provides. Baseline 3 is appropriate.

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 identifies the action ('Executes'), the resource ('BigQuery sql statement'), and the outcome ('returns the results'). It is unambiguous, though it does not explicitly differentiate itself from sibling tools list_tables and get_schema, which are also BigQuery-related.

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

Usage Guidelines2/5

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

No guidance is given about when to use this tool versus list_tables or get_schema. An agent is not told that query should be used for arbitrary SQL while the siblings cover metadata or schema access, nor are any exclusions or prerequisites stated.

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

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. 3 tool updatesv0.1.9
    • First observedget_schema
    • First observedlist_tables
    • First observedquery

TDQS

B3.4/5.0
Disambiguation5/5

Each tool has a distinct and clear purpose: query executes SQL, list_tables enumerates tables, and get_schema describes table structure. There is little risk of an agent selecting the wrong tool for a task.

Naming Consistency4/5

list_tables and get_schema follow a consistent verb_noun snake_case pattern. The lone tool 'query' is a simple verb without a noun object, which is a minor deviation but still clear and natural for the operation.

Tool Count4/5

Three tools is on the minimal side but reasonable for a focused BigQuery read/query server. Each tool serves a distinct need, though the server could support a slightly broader set without feeling bloated.

Completeness4/5

The query tool can execute arbitrary SQL, including DDL/DML, so most BigQuery operations are reachable indirectly. The main gaps are convenience features like listing datasets or managing query jobs, but agents can work around these with SQL and INFORMATION_SCHEMA queries.

Maintenance

ActivityInactive
ResponsivenessNo issues

Resources

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