get_feedFetches recent posts from all Substack subscriptions, newest first. Options include total post limit, date filter, and per-publication cap.
Recent posts across all subscriptions, newest first.
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | Total posts to return. | |
| since | No | Only posts after this point: an ISO date ("2026-09-01") or relative ("7d", "48h"). | |
| per_publication | No | Posts to look at per publication. |
Changes observed during successful MCP inspections.
v0.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds the useful behavioral details that results span all subscriptions and are sorted newest-first, but it does not mention freshness, pagination behavior, or other operational nuances.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single front-loaded sentence with no filler: it communicates scope and ordering in seven words. Every word earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple read-only feed tool with fully documented optional parameters and safety annotations, the description plus schema is largely sufficient. It loses a point only because it does not clarify how it differs from sibling get_recent_posts or describe the expected response shape, which is more important given there is no output schema.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
All three parameters already have descriptive schema entries, giving 100% schema coverage. The description does not add parameter-level detail, so the baseline score of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the resource ('subscription feed'), the scope ('across all subscriptions'), and the ordering ('newest first'), so an agent can tell what this tool returns. It stops short of a 5 because it does not explicitly contrast itself with sibling tools like get_recent_posts or search_posts.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The wording implies this is the tool for browsing an aggregated feed of recent posts from all subscriptions. However, it gives no explicit guidance on when to prefer it over get_recent_posts or search_posts, nor any when-not-to-use conditions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.