substack-mcp

search_posts

Search blog posts by keyword across titles, content, and descriptions to quickly locate relevant articles.

Instructions

Search blog posts by keywords across title, content, and description

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": {
      "query": "<query>"
    },
    "name": "search_posts"
  }
}

Input Schema

Name	Required	Description	Default
`limit`	No	Maximum number of results (default: 10)
`query`	Yes	Search query to find in posts

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Sep 13, 2026

TDQS

B3.1/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states what fields are searched but does not mention read-only nature, safety profile, matching semantics (e.g., AND/OR, fuzzy), ranking, pagination behavior, or authentication requirements, leaving key operational traits unspecified.

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 a single, well-structured sentence with no wasted words. The tool's purpose is front-loaded immediately, making it easy to parse.

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

Completeness3/5

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

For a low-complexity search tool with fully described parameters and no output schema, the description states the search scope but omits usage context relative to the many sibling retrieval tools and provides no behavioral details. It is minimally adequate but leaves clear gaps for an agent choosing among alternatives.

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 the schema already documents both parameters, including the default for 'limit'. The description adds some meaning by indicating that the query searches across title, content, and description, but it does not add syntax, format, or matching details beyond the schema. The baseline of 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?

The description uses a specific verb ('Search') and resource ('blog posts'), and specifies the fields searched ('title, content, and description'). It clearly implies a full-text keyword search, which is distinct from siblings like get_post_by_title or get_posts_by_date_range, but it does not explicitly differentiate itself from those alternatives.

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?

The description gives no explicit guidance on when to use this tool versus alternatives such as list_recent_posts or get_post_by_title. Usage is only implied by the word 'Search' and the search scope, with no stated conditions, exclusions, or alternative selection criteria.

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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