Skip to main content
Glama
dkships

substack-publisher-mcp

by dkships
OverviewSchemaSourceRelated ServersDiscussionsAdmin
TypeScript
Remote

Get Subscriber Counts

get_subscriber_counts
Read-onlyIdempotent

Query daily subscriber counts for a Substack publication, newest first. Get total, paid, free, and source-type breakdown (trial, comp, gift, lifetime, founding) for any date range.

Instructions

Get daily subscriber counts, newest first. Each row has date, total_email_subscribers (free + paid), paid_subscribers, and free_trial, comp, gift, lifetime, and founding counts. Free subscribers = total minus paid. Without dates, returns roughly the last year.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
endDateNoEnd of date range (YYYY-MM-DD, inclusive).
startDateNoStart of date range (YYYY-MM-DD, inclusive).
publicationNoPublication name (e.g., 'ny', 'la'). Required if multiple publications are configured.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed6 schema fields changedv1.2.0
    • changedInput schema / properties / endDate / description
      Previous value: -"End of date range (YYYY-MM-DD)."New value: +"End of date range (YYYY-MM-DD, inclusive)."
    • addedInput schema / properties / endDate / format
      Added value: +"date"
    • changedInput schema / properties / endDate / pattern
      Previous value: -"^\\d{4}-\\d{2}-\\d{2}$"New value: +"^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))$"
    • changedInput schema / properties / startDate / description
      Previous value: -"Start of date range (YYYY-MM-DD)."New value: +"Start of date range (YYYY-MM-DD, inclusive)."
    • addedInput schema / properties / startDate / format
      Added value: +"date"
    • changedInput schema / properties / startDate / pattern
      Previous value: -"^\\d{4}-\\d{2}-\\d{2}$"New value: +"^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))$"
  2. Changed3 schema fields changedv1.1.0
    • removedInput schema / additionalProperties
      Removed value: -false
    • addedInput schema / properties / endDate / pattern
      Added value: +"^\\d{4}-\\d{2}-\\d{2}$"
    • addedInput schema / properties / startDate / pattern
      Added value: +"^\\d{4}-\\d{2}-\\d{2}$"
  3. First observedv1.0.0

TDQS

A4.7/5.0
Behavior5/5

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

Beyond the readOnlyHint/idempotentHint annotations, the description discloses sort order, the exact row fields, the derived 'Free subscribers = total minus paid' relationship, and the default date window. This material detail helps an agent predict output even though no output schema is provided.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

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

The description is four short, information-dense sentences with the core purpose and ordering front-loaded. Every sentence adds value: row contents, the derived field relationship, and the default date behavior. There is no redundancy with the schema or annotations.

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?

Given no output schema, the description names all returned fields, explains their relationship, and states the sort order and default range. Combined with schema-described parameters and safety annotations, the definition is complete for a low-complexity read-only tool.

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?

Schema descriptions already cover all three parameters, so the schema carries the baseline documentation burden. The description adds meaning by clarifying that date parameters are optional and that omitting them yields roughly the last year, which is not stated in the 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?

The description states a specific verb ('Get'), a precise resource ('daily subscriber counts'), and an ordering ('newest first'). It clearly distinguishes itself from sibling tools like get_subscriber or get_post_stats by describing time-series subscriber count rows rather than post stats or an individual subscriber.

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

Usage Guidelines4/5

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

The description makes it clear that this tool is for retrieving daily subscriber counts over time, and it adds useful default behavior: 'Without dates, returns roughly the last year.' It does not explicitly name alternatives or when-not-to-use conditions, but the context is clear enough for an agent to route correctly.

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

Deploy Server

Other Tools