R2 Bucket MCP

upload_file

Upload local files to Cloudflare R2 with customizable destination keys and content types. Returns a public or presigned download URL.

Instructions

Upload a local file to Cloudflare R2. filePath must be an absolute path on the host where this MCP runs. Returns downloadUrl (public CDN URL if R2_PUBLIC_BASE_URL is set, otherwise a presigned URL).

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": {
      "filePath": "<filePath>"
    },
    "name": "upload_file"
  }
}

Input Schema

Name	Required	Description
`filePath`	Yes	Absolute path to the local file on the MCP host
`key`	No	Destination key in the bucket (e.g. vitalo/2.1.0/app-release.apk). Default: file basename
`prefix`	No	Key prefix override (without global R2_KEY_PREFIX)
`contentType`	No	Explicit MIME type; inferred from extension if omitted

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Jun 19, 2026

TDQS

B3.1/5.0

Behavior2/5

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

No annotations are provided, and the description lacks details on behavioral traits such as whether uploads overwrite existing keys, permissions needed, or any side effects. It does mention the return value but is insufficient for full transparency.

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 very concise: three sentences that cover the essential purpose, a critical constraint (absolute path), and the return value. No extraneous information.

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?

The description is fairly complete for a simple upload tool, explaining the file path requirement and return value. However, it does not address overwrite behavior or differentiate from the sibling upload_apk, leaving some contextual gaps.

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 has 100% description coverage, and the description essentially restates the schema information (e.g., default key basename, prefix override). It adds no new meaning beyond what is already in the schema.

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 uploads a local file to Cloudflare R2, specifying 'filePath must be an absolute path'. However, it does not explicitly differentiate from the sibling tool 'upload_apk' which likely has a similar purpose.

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 only mentions that filePath must be an absolute path on the host, but provides no guidance on when to use this tool versus alternatives like upload_apk or the other sibling tools.

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

Deploy Server