substack-mcp

export_to_markdown

Export Substack blog posts to a Markdown file, filtering by date range, search query, or post limit to save selected content locally.

Instructions

Export blog posts to a markdown file

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": {
      "output_path": "<output_path>"
    },
    "name": "export_to_markdown"
  }
}

Input Schema

Name	Required	Description
`limit`	No	Maximum number of posts to export (default: 100)
`query`	No	Optional search query to filter posts
`end_date`	No	Optional end date filter (ISO 8601 format)
`start_date`	No	Optional start date filter (ISO 8601 format)
`output_path`	Yes	Output file path (e.g., ~/Desktop/posts.md)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Sep 13, 2026

TDQS

C2.9/5.0

Behavior2/5

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

With no annotations, the description carries the full behavioral burden. It implies a file write to output_path but never states whether an existing file is overwritten or appended, whether the target directory must exist, whether this requires write permissions, or how multiple posts are combined into one markdown file.

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 front-loaded sentence with zero filler. It is efficient, though its brevity borders on under-specification for a tool that writes to disk.

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 five-parameter tool with a filesystem side effect and no annotations or output schema, the description leaves key questions unanswered: overwrite behavior, file format layout, error handling, and whether the date/query filters apply to the export. It is too thin for a mutation tool.

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%, so all five parameters (limit, query, dates, output_path) are already documented in the schema. The description adds no syntax, format, or interaction details beyond that, so the 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 (export) and resource (blog posts) plus the output form (markdown file), so the core action is unambiguous. However, it does nothing to distinguish itself from sibling read tools like list_recent_posts or search_posts, and it's unclear whether it exports all posts or a filtered set.

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 guidance and no mention of alternatives. It doesn't tell the agent when to reach for this tool instead of search_posts or get_posts_by_date_range, or whether the filters (query, start_date, end_date) should be used to narrow the export.

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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