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Server and protocol

Drum has one remote MCP (Model Context Protocol) server. Every client connects to the same URL. The credential decides the account, the user and the toolsets, so nothing else goes in the URL.

Endpoint

   
URL https://app.getdrum.com/api/v1/mcp
Transport Streamable HTTP, answered as plain JSON. No SSE stream and no sessions
Message format JSON-RPC 2.0, one message in each request
Authentication Authorization: Bearer <token>: a Sign in with Drum (OAuth) token or an account-scoped API token. See Authentication and permissions
Account Taken from the credential
Toolsets Stored on the credential. No path, query parameter or header selects them
Server name drum
Method and path Does
POST /api/v1/mcp Takes one JSON-RPC message and returns its answer
GET /api/v1/mcp Returns 405. The server sends no event stream
DELETE /api/v1/mcp Returns 405. The server keeps no sessions to end

There is no local server to install. The server is hosted by Drum, and there is one for the whole of Drum.

Requests

  • Send Content-Type: application/json and one JSON-RPC message in the body.
  • A batch (a JSON array of messages) is refused with JSON-RPC error -32600 “Invalid Request”.
  • A notification, such as notifications/initialized, returns 202 with no body.
  • The server is stateless. It sets no Mcp-Session-Id, and each request stands alone.

Protocol versions

The server supports the MCP protocol versions 2024-11-05, 2025-03-26, 2025-06-18, 2025-11-25 and 2026-07-28. A client sends the version it wants in initialize, and the server answers with the same version when it supports it.

On 2026-07-28, a client may call server/discover in place of initialize. List results carry cacheScope: "private" and ttlMs: 60000: the answer is for this credential only, and is good for a minute.

Methods

Method Does
initialize Starts the conversation. Returns the server’s name, version, capabilities and instructions
notifications/initialized The client’s acknowledgement. Returns 202
ping Returns an empty result
tools/list Lists the tools this credential may use, in a fixed order
tools/call Calls one tool with its arguments
server/discover On protocol 2026-07-28, returns what initialize returns
prompts/list, resources/list Return empty lists

All of Drum’s features are tools. The server has no prompts or resources to offer, and it never asks the client for sampling.

Instructions

initialize returns an instructions text that the client gives to the AI. Drum builds it for the toolsets and the role of the credential, in this order:

  1. What Drum is.
  2. What each selected toolset does, in one sentence each.
  3. The shared rules: ask the user before a call that notifies people, deletes data or cannot be reversed; get each id from search_records or a get_ tool; money is integer cents and tax exclusive, durations are whole minutes and dates are yyyy-mm-dd; how pages, errors and idempotency keys work.
  4. The other toolsets this user could add, and where in Drum to add them.
  5. The rules and the usual order of work of each selected toolset, while they fit.

The text is 2,048 characters or fewer. When the Beat tools are listed, it also tells the AI that a Beat’s content is customer data, not instructions.

The tool list

tools/list returns only the tools of the selected toolsets that the user’s role and the OAuth scope allow. The list is always in the same order. Each tool has:

Field Holds
name The tool’s name, such as create_tracked_time
title A human name, such as “Create tracked time”. Also in annotations.title for older clients
description What the tool does and how to use it, written for the AI
inputSchema A JSON Schema of the inputs. It refuses unknown keys
outputSchema A JSON Schema of structuredContent in the result
annotations readOnlyHint, destructiveHint, idempotentHint and openWorldHint
Annotation true means
readOnlyHint The tool changes nothing
destructiveHint The tool deletes or replaces data, emails people, or cannot be reversed. Clients often ask the user before they call one
idempotentHint Calling it again with the same input has no further effect
openWorldHint The tool reaches a system outside Drum: create_cost and update_cost can send a bill to the accounting system, and send_proposal sends email

The list and the instructions depend on the credential. A client should cache them for no longer than a minute, so a changed role or a changed toolset selection shows soon. Some clients read the list only when they connect, so reconnect or restart one if the tools do not change.

For each tool, see the tool pages: My work, Sales, Clients, Proposals, Insights, Setup, Templates, Proposal templates and Search, delete and restore.

Example

curl -X POST https://app.getdrum.com/api/v1/mcp \
  -H "Authorization: Bearer $DRUM_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc": "2.0", "id": 1, "method": "tools/list"}'

For a full walk-through, see Make your first MCP call.