Spacepal MCP Server

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List Spaces

list_spaces

Read-onlyIdempotent

Lists every macOS Space on every display, including desktop number, name, note, apps, and active status; use it first to obtain valid Space identifiers for other tools.

Instructions

List every macOS Space (desktop) on every display: desktop number, name, note, the apps with windows on it, and which one is active. Read-only. Call this first to get valid Space numbers and names for the other tools. Fails if Spacepal is not running or has not written its list yet.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "list_spaces"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
`spaces`	Yes
`current`	Yes	Name of the active Space

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedv0.2.3Nov 6, 2026
- changedOutput schema / properties / spaces / items / additionalProperties
```
Previous value: -trueNew value: +{}
```
- addedOutput schema / properties / spaces / items / properties / number / maximum
```
Added value: +9007199254740991
```
- addedOutput schema / properties / spaces / items / properties / number / minimum
```
Added value: +-9007199254740991
```

Changed1 schema field changedv0.2.2Nov 6, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "current": {
+      "description": "Name of the active Space",
+      "type": "string"
+    },
+    "spaces": {
+      "items": {
+        "additionalProperties": true,
+        "properties": {
+          "apps": {
+            "description": "Apps with a window on this Space",
+            "items": {
+              "type": "string"
+            },
+            "type": "array"
+          },
+          "color": {
+            "description": "Colour as #RRGGBB",
+            "type": "string"
+          },
+          "display": {
+            "description": "Id of the display the Space is on",
+            "type": "string"
+          },
+          "id": {
+            "description": "Stable id of the Space",
+            "type": "string"
+          },
+          "isActive": {
+            "description": "True for the Space currently shown on its display",
+            "type": "boolean"
+          },
+          "isFullscreen": {
+            "description": "True for an app's full-screen Space",
+            "type": "boolean"
+          },
+          "name": {
+            "description": "Name shown in Spacepal, or \"Desktop N\" if unnamed",
+            "type": "string"
+          },
+          "note": {
+            "description": "The user's note about what the Space is for",
+            "type": "string"
+          },
+          "number": {
+            "description": "Desktop number on its display; absent for full-screen Spaces",
+            "type": "integer"
+          }
+        },
+        "required": [
+          "id",
+          "name",
+          "display",
+          "isActive",
+          "isFullscreen",
+          "apps"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "current",
+    "spaces"
+  ],
+  "type": "object"
+}

First observedv0.1.0Nov 5, 2026

TDQS

A4.7/5.0

Behavior4/5

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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), yet the description still adds real value by disclosing the failure mode: Spacepal not running or its list not yet written. It does not cover latency, freshness/staleness of the cached list, or pagination, so it stops short of 5.

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?

Three short sentences, front-loaded with the operation and scope, then the read-only nature, then the routing advice and failure condition. No sentence is filler.

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?

For a no-parameter read tool with full annotation coverage and an output schema, the description supplies everything an agent needs: what it returns, that it is safe, that it should be called first to obtain Space numbers, and what makes it fail.

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

Parameters4/5

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

Zero parameters, so the baseline is 4 and there is nothing for the description to disambiguate. The enumerated output fields are informational only and are already covered by the output schema.

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 every macOS Space (desktop)') plus scope ('on every display') and enumerates the returned fields: number, name, note, apps with windows, active flag. An agent can distinguish it from siblings like current_space (single space) or list_profiles without opening a 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 explicit ordering guidance: 'Call this first to get valid Space numbers and names for the other tools,' which tells the agent both when to use it and why. It also states the precondition under which it fails, so the agent knows what to check before relying on the result.

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