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Google Calendar MCP Server

by despinozap
OverviewSchemaSourceRelated ServersDiscussionsAdmin
TypeScript
Remote

MCP server for Google Calendar

Credentials

The credentials.json file is needed to authenticate againts the Google services. To generate the file, the following steps must be performed:

  1. Visit the Google Cloud Platform website

  2. Crete a new project (or use an existant one)

  3. Into the APIs & Services section, enable the Google Calendar API service

  4. Go to Credentials and generate a new credential as Service Account

  5. Copy the service account's email generated. It will be needed to share the calendar with it

  6. After the credential is created, a JSON file will be able to download. Place it into the root of this project and name it as credentials.json

Related MCP server: Google Calendar MCP Server

Calendar sharing

To interact with a calendar, it needs to be shared with the service account previously created to access it following these steps:

  1. Visit the Google Calendar website

  2. Into the sidebar, place on the target calendar, click the three dots (...) and then go to Settings and sharing

  3. Go the Shared with and add the email address for the service account copied previously when the credential was created

  4. Go to Integrate calendar and copy the Calendar ID value

Inspector

While developing, you can use the inspector to debug the server. To do this:

npm run inspector

Build MCP Server

Before adding the MCP server to the configuration file, you need to build it. The build process will create a Docker image that can be run in WSL.

npm run build
docker build -t mcpserver-googlecalendar .

Add MCP Server

To add the MCP server, add to the configuration file and paste the Calendar ID copied previously:

{
  "mcpServers": {
    "google-calendar": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "-e",
        "GOOGLE_CALENDAR_ID",
        "mcpserver-googlecalendar"
      ],
      "env": {
        "GOOGLE_CALENDAR_ID": "[CALENDAR_ID_HERE]"
      }
    }
  }
}

Available Tools

1 tool
get_calendar_eventsC

Get calendar events from Google Calendar. By default, it retrieves events from the last 3 months.

ParametersJSON Schema
NameRequiredDescriptionDefault
startDateNoThe start date for the event search. ISO 8601 format.
endDateNoThe end date for the event search. ISO 8601 format.

TDQS

C2.9/5.0
Behavior2/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions the default time range, which is useful, but fails to cover critical aspects like pagination, rate limits, error handling, or authentication requirements for a read operation, leaving significant gaps in understanding the tool's behavior.

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?

The description is brief and front-loaded with the core purpose, consisting of two efficient sentences. However, it could be more structured by explicitly separating purpose from behavioral details, and the second sentence slightly overlaps with parameter semantics without adding significant value.

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

Completeness2/5

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

Given the complexity of a calendar events tool with no annotations and no output schema, the description is incomplete. It lacks details on return format (e.g., event fields, pagination), error cases, and authentication, making it inadequate for an agent to fully understand how to use and interpret results from this tool.

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?

The input schema has 100% description coverage, clearly documenting both parameters with ISO 8601 format. The description adds no additional parameter semantics beyond implying a default time range if parameters are omitted, which aligns with the schema's optional nature but doesn't enhance understanding of the parameters themselves.

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 clearly states the verb ('Get') and resource ('calendar events from Google Calendar'), making the purpose unambiguous. It doesn't need to distinguish from siblings since none exist, but it could be slightly more specific about what 'get' entails (e.g., listing vs. fetching details).

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 provides minimal guidance—only mentioning the default time range of 'last 3 months.' It lacks explicit when-to-use instructions, prerequisites (e.g., authentication needs), or alternatives, leaving the agent with little context for optimal tool selection.

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

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

  1. 1 tool update
    • First observedget_calendar_events
Deploy Server
One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

TDQS

B3/5.0

Scored across 1 tool

Disambiguation5/5

With only one tool, there is no possibility of ambiguity or overlap between tools. The tool's purpose is clearly defined and distinct by default.

Naming Consistency5/5

A single tool inherently has perfect naming consistency, as there are no other tools to compare it against for patterns or conventions.

Tool Count2/5

One tool is too few for a Google Calendar server, as it severely limits functionality. A calendar domain typically requires CRUD operations (e.g., create_event, update_event, delete_event) and other features like listing calendars or managing attendees, making this server incomplete and impractical for most agent workflows.

Completeness1/5

The server is severely incomplete for a Google Calendar domain. It only provides read access to events, lacking essential operations such as creating, updating, or deleting events, managing calendars, or handling recurring events, which will cause frequent agent failures in typical calendar-related tasks.

Maintenance

ActivityInactive
ResponsivenessNo issues

Resources

Related MCP Connectors

Related MCP Servers

  • GCAL-MCP

    annyzhou
    A
    license
    Not graded
    quality
    D
    maintenance
    A Model Context Protocol server that provides read-only access to the Google Calendar API v3. It enables users to list calendars, search for events, check free/busy availability, and retrieve calendar settings.
    MIT

  • gcal-mcp

    jdcc
    F
    license
    Not graded
    quality
    D
    maintenance
    An MCP server that provides integration with Google Calendar, allowing users to list calendars and manage events. It enables searching, creating, and modifying calendar entries through tools designed for the Model Context Protocol.
    -