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Export subscribers

export_subscribers

Read-onlyIdempotent

Export the full subscriber list as a CSV download link with row count, including email, name, subscription type, activity rating and start date. Returns a link valid for 24 hours.

Instructions

The full subscriber list as a CSV download link, with the row count.

Builds the same CSV as Export in the subscriber dashboard: email, name, subscription type, activity rating and start date. Substack builds the file in the background; the call waits up to about a minute and otherwise asks you to try again later. The link needs no sign-in and works until expires_at, 24 hours when we recorded it. For filtered pages use list_subscribers.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "export_subscribers"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 24, 2026

TDQS

A4.8/5.0

Behavior5/5

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

Annotations only say read-only/idempotent/open-world; the description adds the operationally important facts: the file is built asynchronously, the call blocks for roughly a minute, the link requires no authentication, and it expires at expires_at (24 hours when observed). These are exactly the traits an agent cannot infer from annotations or an empty schema.

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?

Front-loaded with the return value and CSV contents, then the async/expiry caveats and the alternative. Mostly earns its space, though the hedge '24 hours when we recorded it' slightly muddies an otherwise precise expiry statement.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema exists, yet the description fully covers the return (link plus row count, column list, expiry) and the async failure mode. An agent has everything needed to call it and interpret the result.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Zero parameters, so the baseline is 4. The description usefully clarifies that the export is unfiltered and that filtering belongs to a different tool, which compensates for an empty schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource (export the full subscriber list) plus the return shape — CSV download link with row count. Explicitly contrasts with the dashboard 'Export' equivalent and with list_subscribers, so an agent can tell it apart from the filtered-listing sibling instantly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Names the alternative tool and the condition that selects it: 'For filtered pages use list_subscribers.' It also tells the agent what to do on the failure path — retry later if the background build takes more than about a minute.

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