substack-saved-mcp

Overview Schema Source Related Servers Discussions Admin

get_saved_post

Retrieve a saved Substack post's cached details, timestamps, and content by URL or local ID; use the post URL for numeric Substack post IDs and fetch content first if content_text is empty.

Instructions

Retrieve full cached post details, timestamps (published_at and saved_at), and content by URL or local ID.

An all-digit value is always treated as the local ID, so a numeric Substack post ID will not match; pass the post URL instead. content_text is empty until get_post_content has fetched the post.

Input Schema

Name	Required	Description	Default
`url_or_id`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.4.0Nov 1, 2026

changedOutput schema / properties / result / anyOf

Previous value: -[
-  {
-    "description": "Represents a Substack post record stored in SQLite.",
-    "properties": {
-      "audience": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "author_name": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "content_text": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "created_at": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "excerpt": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "id": {
-        "anyOf": [
-          {
-            "type": "integer"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "image_url": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "is_fully_read": {
-        "readOnly": true,
-        "type": "boolean"
-      },
-      "is_paywalled": {
-        "default": 0,
-        "type": "integer"
-      },
-      "is_saved": {
-        "default": 1,
-        "type": "integer"
-      },
-      "is_viewed": {
-        "default": 0,
-        "type": "integer"
-      },
-      "max_read_progress": {
-        "anyOf": [
-          {
-            "type": "number"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "minutes_remaining": {
-        "anyOf": [
-          {
-            "type": "integer"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "readOnly": true
-      },
-      "publication_name": {
-        "type": "string"
-      },
-      "publication_url": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "published_at": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "read_progress": {
-        "anyOf": [
-          {
-            "type": "number"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "reading_time_minutes": {
-        "anyOf": [
-          {
-            "type": "integer"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "saved_at": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "substack_post_id": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "title": {
-        "type": "string"
-      },
-      "unsaved_at": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "updated_at": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "url": {
-        "type": "string"
-      },
-      "word_count": {
-        "anyOf": [
-          {
-            "type": "integer"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      }
-    },
-    "required": [
-      "url",
-      "title",
-      "publication_name",
-      "is_fully_read",
-      "minutes_remaining"
-    ],
-    "type": "object"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "description": "Represents a Substack post record stored in SQLite.",
+    "properties": {
+      "audience": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "author_name": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "content_text": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "created_at": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "excerpt": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "id": {
+        "anyOf": [
+          {
+            "type": "integer"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "image_url": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "is_fully_read": {
+        "readOnly": true,
+        "type": "boolean"
+      },
+      "is_paywalled": {
+        "default": 0,
+        "type": "integer"
+      },
+      "is_saved": {
+        "default": 1,
+        "type": "integer"
+      },
+      "is_viewed": {
+        "default": 0,
+        "type": "integer"
+      },
+      "max_read_progress": {
+        "anyOf": [
+          {
+            "type": "number"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "minutes_remaining": {
+        "anyOf": [
+          {
+            "type": "integer"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "readOnly": true
+      },
+      "publication_name": {
+        "type": "string"
+      },
+      "publication_url": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "published_at": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "read_progress": {
+        "anyOf": [
+          {
+            "type": "number"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "reading_time_minutes": {
+        "anyOf": [
+          {
+            "type": "integer"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "saved_at": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "seen_at": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "substack_post_id": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "title": {
+        "type": "string"
+      },
+      "unsaved_at": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "updated_at": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "url": {
+        "type": "string"
+      },
+      "word_count": {
+        "anyOf": [
+          {
+            "type": "integer"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      }
+    },
+    "required": [
+      "url",
+      "title",
+      "publication_name",
+      "is_fully_read",
+      "minutes_remaining"
+    ],
+    "type": "object"
+  },
+  {
+    "type": "null"
+  }
+]

Changed1 schema field changedv0.3.1Aug 22, 2026

changedOutput schema / properties / result / anyOf

Previous value: -[
-  {
-    "description": "Represents a Substack post record stored in SQLite.",
-    "properties": {
-      "audience": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "author_name": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "content_text": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "created_at": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "excerpt": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "id": {
-        "anyOf": [
-          {
-            "type": "integer"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "image_url": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "is_paywalled": {
-        "default": 0,
-        "type": "integer"
-      },
-      "is_saved": {
-        "default": 1,
-        "type": "integer"
-      },
-      "publication_name": {
-        "type": "string"
-      },
-      "publication_url": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "published_at": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "reading_time_minutes": {
-        "anyOf": [
-          {
-            "type": "integer"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "saved_at": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "substack_post_id": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "title": {
-        "type": "string"
-      },
-      "unsaved_at": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "updated_at": {
-        "anyOf": [
-          {
-            "type": "string"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      },
-      "url": {
-        "type": "string"
-      },
-      "word_count": {
-        "anyOf": [
-          {
-            "type": "integer"
-          },
-          {
-            "type": "null"
-          }
-        ],
-        "default": null
-      }
-    },
-    "required": [
-      "url",
-      "title",
-      "publication_name"
-    ],
-    "type": "object"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "description": "Represents a Substack post record stored in SQLite.",
+    "properties": {
+      "audience": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "author_name": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "content_text": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "created_at": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "excerpt": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "id": {
+        "anyOf": [
+          {
+            "type": "integer"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "image_url": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "is_fully_read": {
+        "readOnly": true,
+        "type": "boolean"
+      },
+      "is_paywalled": {
+        "default": 0,
+        "type": "integer"
+      },
+      "is_saved": {
+        "default": 1,
+        "type": "integer"
+      },
+      "is_viewed": {
+        "default": 0,
+        "type": "integer"
+      },
+      "max_read_progress": {
+        "anyOf": [
+          {
+            "type": "number"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "minutes_remaining": {
+        "anyOf": [
+          {
+            "type": "integer"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "readOnly": true
+      },
+      "publication_name": {
+        "type": "string"
+      },
+      "publication_url": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "published_at": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "read_progress": {
+        "anyOf": [
+          {
+            "type": "number"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "reading_time_minutes": {
+        "anyOf": [
+          {
+            "type": "integer"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "saved_at": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "substack_post_id": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "title": {
+        "type": "string"
+      },
+      "unsaved_at": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "updated_at": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      },
+      "url": {
+        "type": "string"
+      },
+      "word_count": {
+        "anyOf": [
+          {
+            "type": "integer"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null
+      }
+    },
+    "required": [
+      "url",
+      "title",
+      "publication_name",
+      "is_fully_read",
+      "minutes_remaining"
+    ],
+    "type": "object"
+  },
+  {
+    "type": "null"
+  }
+]

First observedv0.1.0Aug 2, 2026

TDQS

A5/5.0

Behavior5/5

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

It clearly discloses key behavioral traits: the data is 'cached,' and crucially, the 'content_text is empty until get_post_content has fetched the post.' This establishes a necessary two-step workflow for the AI agent and manages expectations about what the tool returns on its own.

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 front-loaded, starting with the core function and immediately following up with the most critical operational details (input rules and content fetching limitations). Every sentence is required to define the tool's behavior accurately.

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 the complexity of the input parsing rules and the staged delivery of content (cache vs. full text), the description is maximally complete for guiding an agent on how and when to use this specific API endpoint.

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

Parameters5/5

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

Since schema coverage is 0%, the description must convey complex logic. It elaborates that input parameters are context-dependent based on their format (all-digit vs. non-numeric string), which is essential for correct invocation.

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 is highly specific, stating that the tool retrieves 'full cached post details,' including specific fields like timestamps. It clearly defines the input scope (URL or local ID) and implicitly differentiates itself by mentioning 'cached' details versus requiring a separate call for content.

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?

It provides critical guidance on input formats: 'An all-digit value is always treated as the local ID,' and warns against using numeric Substack IDs because they will fail. This explicitly dictates how the agent must structure its input based on the required data.

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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