spinnaker-mcp

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List clusters

list_clusters

Read-onlyIdempotent

Lists Spinnaker application cluster names grouped by account, letting you discover available clusters before inspecting a specific one.

Instructions

List all cluster names for a Spinnaker application, grouped by account. Use this to discover clusters before drilling into a specific one with get_cluster. Returns JSON object mapping account names to arrays of cluster names.

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": {
      "application": "<application>"
    },
    "name": "list_clusters"
  }
}

Input Schema

Name	Required	Description	Default
`application`	Yes	Application name as registered in Spinnaker

Output Schema

Name	Required	Description	Default
`count`	No	Number of records in items.
`items`	No	The records, when Gate answered with a list.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.4.1Nov 1, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "description": "The Gate response. A JSON object from Gate comes back as is; a JSON array comes back as {items, count}.",
+  "properties": {
+    "count": {
+      "description": "Number of records in items.",
+      "minimum": 0,
+      "type": "integer"
+    },
+    "items": {
+      "description": "The records, when Gate answered with a list.",
+      "type": "array"
+    }
+  },
+  "type": "object"
+}

First observedv0.1.0Apr 23, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds the grouping behavior (results keyed by account) which is a real behavioral trait beyond the annotations, though it says nothing about ordering, empty accounts, or error cases.

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?

Three short sentences, front-loaded with purpose, then usage routing, then return shape. The return-shape sentence is partly redundant given an output schema exists, but it is short enough not to be wasteful.

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?

Single required parameter, full schema coverage, rich annotations, and an output schema that carries return details. The description supplies purpose, routing, and grouping semantics, so an agent has everything needed to call it correctly.

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% and the single 'application' parameter is documented there as 'Application name as registered in Spinnaker'. The description only restates that the application is a Spinnaker application, adding no new semantics such as format or naming constraints.

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?

States a specific verb and resource ('List all cluster names') plus the scoping dimension ('for a Spinnaker application, grouped by account'). It also explicitly contrasts with the sibling get_cluster, so an agent can distinguish the two without opening either schema.

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?

Gives an explicit routing rule: 'Use this to discover clusters before drilling into a specific one with get_cluster.' The alternative tool and the condition that selects it are both named, leaving nothing to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.