MCP Supabase Server

supabase_upload_file

Upload a file to a Supabase storage bucket by providing the bucket name, file path, and base64 or text data.

Instructions

Upload a file to a Supabase storage 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": "<bucket>",
      "path": "<path>",
      "data": "<data>"
    },
    "name": "supabase_upload_file"
  }
}

Input Schema

Name	Required	Description	Default
`data`	Yes	File data (base64 encoded or text)
`path`	Yes	File path within the bucket
`bucket`	Yes	Storage bucket name
`contentType`	No	MIME type of the file	application/octet-stream

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 13, 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. It says 'Upload' but doesn't disclose whether existing files at the same path are overwritten, whether the operation requires specific bucket policies or authentication, whether it returns a public URL, or whether there are size/content restrictions. For a mutation tool with zero annotation coverage, 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.

Conciseness4/5

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

A single, efficient sentence with no wasted words and the core action front-loaded. It is appropriately sized for the simplicity of the operation, though it could be slightly more definitive about scope.

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?

For a mutation tool with no annotations, no output schema, and 3 required parameters, the description should explain overwrite behavior, auth/permission requirements, and any return value (e.g., public URL). None of that is present. The high schema coverage helps parameters, but behavioral context is missing.

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% – all four parameters (bucket, path, data, contentType) are documented in the schema with clear descriptions. The tool description adds nothing beyond what the schema already provides, which is the expected baseline when schema coverage is high.

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?

Clear verb+resource: 'Upload a file to a Supabase storage bucket.' An agent can immediately distinguish this from siblings like supabase_list_files or supabase_delete_file by the verb and target resource. However, it doesn't differentiate against other write siblings like supabase_insert (which writes to tables, not storage), leaving some ambiguity about storage-vs-table operations.

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 on when to use this tool versus alternatives. It doesn't mention prerequisites (does the bucket need to exist?), overwrite behavior, file size limits, or when to prefer supabase_insert for structured data vs. file upload for storage objects. An agent must infer usage from the name alone.

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

Deploy Server