TimeTree MCP Server

list_calendars

Read-only

List active TimeTree calendars with IDs, names, and members to obtain the calendar_id required by all other tools; use member names to select the right calendar.

Instructions

List your active TimeTree calendars with their IDs, names, and members. Call this first: every other tool needs a calendar_id from here. Use the member names to pick a calendar when the user mentions a person (e.g., "events with [name]").

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_calendars"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
`total`	Yes
`calendars`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.7.0Oct 22, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "calendars": {
+      "items": {
+        "properties": {
+          "alias_code": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "id": {
+            "description": "calendar_id for the other tools",
+            "type": "string"
+          },
+          "is_active": {
+            "type": "boolean"
+          },
+          "name": {
+            "type": "string"
+          },
+          "users": {
+            "items": {
+              "properties": {
+                "name": {
+                  "type": "string"
+                },
+                "role": {
+                  "enum": [
+                    "owner",
+                    "member"
+                  ],
+                  "type": "string"
+                }
+              },
+              "type": "object"
+            },
+            "type": "array"
+          }
+        },
+        "required": [
+          "id",
+          "name"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "total": {
+      "type": "number"
+    }
+  },
+  "required": [
+    "calendars",
+    "total"
+  ],
+  "type": "object"
+}

First observedv0.3.0May 27, 2026

TDQS

A4.7/5.0

Behavior4/5

Does 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 real behavioral context beyond that: only *active* calendars are returned (inactive ones are silently omitted) and the member list is exposed. It stops short of noting auth requirements or whether membership is trimmed for large calendars.

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 core action, then the dependency rule, then the practical selection tip. Nothing is redundant with the schema or annotations.

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?

A zero-parameter read tool with an output schema and read-only annotations needs only purpose, sequencing, and a usage tip — all three are present. No return-value documentation is required since the output schema covers it.

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 of 4 applies and there is nothing for the description to disambiguate. The description correctly spends no words re-explaining an empty 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 your active TimeTree calendars") and names exactly what is returned (IDs, names, members). The line "Call this first: every other tool needs a calendar_id from here" cleanly separates it from siblings like get_calendar_members or get_events, which all require an ID this tool supplies.

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 sequencing rule (call this first, all other tools depend on its calendar_id) plus a concrete selection heuristic (match member names when the user names a person, with an example). This is prescriptive when-to-use guidance rather than vague context.

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