MCP Supabase Server

supabase_rpc

Call a stored function or RPC endpoint in Supabase by passing the function name and arguments.

Instructions

Call a stored function or RPC endpoint in Supabase.

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": {
      "function": "<function>"
    },
    "name": "supabase_rpc"
  }
}

Input Schema

Name	Required	Description	Default
`args`	No	Arguments to pass to the function
`function`	Yes	Name of the stored function to call

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 provided, so the description carries full burden. It does not state whether calls are read-only or mutating, whether the function executes with elevated privileges, what errors look like, or any side-effect characteristics. For an RPC invocation tool this leaves substantial unknowns.

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 waste and front-loaded verb. Slightly under-specified rather than verbose.

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-capable RPC tool with no annotations, no output schema, and a free-form args object, the description should disclose side effects, privilege/auth requirements, and how it relates to sibling tools like supabase_execute_sql. None of that is present.

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%: both 'function' (name) and 'args' (arguments object) are documented in the schema. The description adds no format or semantic detail beyond the schema, so baseline 3 applies.

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?

States a specific verb (Call) and resource (stored function / RPC endpoint in Supabase). The dual phrasing 'stored function or RPC endpoint' is slightly ambiguous but the intent is clear. It does not differentiate from siblings like supabase_execute_sql, which is a meaningful gap given 12 siblings.

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 when-to-use, when-not-to-use, or alternative guidance. An agent seeing both supabase_rpc and supabase_execute_sql has no description-level signal about which to pick.

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

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