MinIO MCP Server

minio_upload_file

Upload local files to MinIO object storage buckets using this MCP server tool. Specify bucket name, object name, and file path to store data in S3-compatible storage.

Instructions

Upload a local file to MinIO bucket

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": {
      "bucket_name": "<bucket_name>",
      "object_name": "<object_name>",
      "file_path": "<file_path>"
    },
    "name": "minio_upload_file"
  }
}

Input Schema

Name	Required	Description
`bucket_name`	Yes	Name of the bucket
`object_name`	Yes	Name for the object in the bucket
`file_path`	Yes	Path to the local file to upload
`content_type`	No	MIME type of the content (auto-detected if not provided)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Mar 9, 2026

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 behavioral disclosure. It states the action ('Upload') but doesn't cover critical aspects like authentication requirements, error handling (e.g., what happens if the bucket doesn't exist), rate limits, or whether the operation is idempotent. For a mutation tool with zero annotation coverage, this leaves significant gaps in understanding its behavior.

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, efficient sentence that gets straight to the point with zero wasted words. It's front-loaded with the core action and resource, making it easy to parse quickly. Every word earns its place.

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?

Given this is a mutation tool (upload implies write) with no annotations and no output schema, the description is incomplete. It doesn't address behavioral traits like side effects, error conditions, or response format. For a tool that modifies state, more context is needed to use it safely and effectively.

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?

Schema description coverage is 100%, with all parameters clearly documented in the input schema. The description doesn't add any meaningful semantic context beyond what the schema provides (e.g., it doesn't explain parameter interactions or constraints). This meets the baseline of 3 since the schema does the heavy lifting, but no extra value is added.

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 action ('Upload') and target ('a local file to MinIO bucket'), making the purpose immediately understandable. However, it doesn't differentiate this tool from sibling tools like 'minio_put_object' or 'minio_copy_object', which might have overlapping functionality. The description is specific but lacks sibling distinction.

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 provides no guidance on when to use this tool versus alternatives like 'minio_put_object' or 'minio_copy_object'. It doesn't mention prerequisites (e.g., bucket must exist), exclusions, or typical use cases. Without this context, an agent might struggle to choose between similar tools.

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

Deploy Server