> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hasmcp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# What payload is needed to create an MCP server tool association?

> A deep breakdown of the required POST payload and its rigid relationship mappings.

# Payload for Creating a Tool Association

When granting a new executable capability to your MCP server via the `/servers/{serverId}/tools` endpoint, the integration relies heavily upon explicitly proving the relationship framework.

## The Rigid Request Structure

Unlike updating an abstract entity (which only requires localized changes), forming an association is an absolute mapping mechanism. The payload mandates constructing a [`CreateServerToolRequest`](/api-reference/servers/tools/create-mcp-server-tool-association) housing a `tool` block.

### Mandatory Fields

The `tool` object strictly requires all three of these properties to execute correctly:

* **`serverID`** *(string)*: The 11-character hash dictating the target MCP environment. This **must** perfectly match the `{serverId}` deployed in the URL path of your POST request.
* **`providerID`** *(string)*: The 11-character hash indicating the root API Provider which currently "owns" the original tool logic.
* **`toolID`** *(string)*: The specific 11-character hash that points exactly to the executable tool configuration living inside the provider.

### The JSON Format

```json theme={null}
{
 "tool": {
 "serverID": "sE8vKd2qLp9",
 "providerID": "kSuB9Gf6aD4",
 "toolID": "tH4mZw9xV2n"
 }
}
```

## Why are all three IDs required?

HasMCP thrives on secure multi-provider routing. By forcing the inclusion of the `providerID` alongside the `toolID`, the system definitively protects against traversal or orphaned ID injections. The controller actively verifies:

1. Does the specified `providerID` exist?
2. Does the specified `toolID` physically belong to that explicit Provider?
3. If valid, lock that verified capability to the `serverID`.