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Klaviyo

by io.github.pipeworx-io
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Klaviyo List Lists

klaviyo_list_lists
Read-onlyIdempotent

Get all email lists in your account. Returns list IDs, names, subscriber counts, and creation dates.

Input Schema

NameRequiredDescriptionDefault
_apiKeyYesKlaviyo private API key

Output Schema

NameRequiredDescriptionDefault
dataNoArray of list objects

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changed
    • changedOutput schema / (root)
      Previous value: -nullNew value: +{
+  "properties": {
+    "data": {
+      "description": "Array of list objects",
+      "items": {
+        "properties": {
+          "attributes": {
+            "description": "List attributes",
+            "properties": {
+              "created_at": {
+                "description": "Creation timestamp",
+                "type": "string"
+              },
+              "name": {
+                "description": "List name",
+                "type": "string"
+              },
+              "profile_count": {
+                "description": "Number of subscribers",
+                "type": "number"
+              },
+              "updated_at": {
+                "description": "Last update timestamp",
+                "type": "string"
+              }
+            },
+            "type": "object"
+          },
+          "id": {
+            "description": "List ID",
+            "type": "string"
+          },
+          "type": {
+            "description": "Resource type (list)",
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "type": "array"
+    }
+  },
+  "type": "object"
+}
  2. Changed1 schema field changed
    • addedInput schema / examples
      Added value: +[
+  {
+    "_apiKey": "your-klaviyo-api-key"
+  }
+]
  3. First observed

TDQS

A4/5.0
Behavior3/5

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

Annotations already disclose read-only, idempotent, non-destructive behavior, lowering the bar for the description. The description adds return field details (list IDs, names, subscriber counts, creation dates), but this is output-oriented rather than deep behavioral context (e.g., pagination, rate limits, auth specifics). It doesn't contradict annotations, and the added value is modest, aligning with a 3.

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 two sentences, front-loaded with the core action ('Get all email lists') followed by return contents. There is zero fluff or redundancy, making it perfectly concise.

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

Completeness4/5

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

For a simple list tool with one parameter, rich annotations, and an output schema, the description covers the essential purpose and return data. It doesn't mention pagination or limits, but 'all' suggests completeness. Given the low complexity, this is nearly complete, though a note about data freshness (given openWorldHint) could push it higher.

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% for the single parameter (_apiKey), so the description doesn't need to explain it. The description adds no extra meaning beyond the schema, meeting the baseline of 3 for high schema coverage.

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 uses a specific verb and resource ('Get all email lists') and clearly distinguishes this from sibling tools like klaviyo_list_campaigns and klaviyo_list_profiles by focusing on email lists. It also specifies the return payload (IDs, names, subscriber counts, creation dates), making the purpose unambiguous.

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 implies when to use the tool (when you need email lists) by clearly scoping to 'email lists in your account.' While it doesn't explicitly mention alternatives or exclusions, the context is sufficient for an agent to differentiate from sibling list tools. It lacks explicit 'when-not-to-use' guidance, so it falls short of a 5.

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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