A1 Google Calendar MCP

Save the OAuth client

set_client

Idempotent

Saves OAuth client credentials from a Google Cloud Console JSON file to enable Google Calendar access. Provide the file path, then call start_login.

Instructions

Saves the OAuth client credentials from the JSON file downloaded from Google Cloud Console ('Download JSON' on a Desktop-app client). Pass the file PATH — the secret must never be pasted into the chat. The client is stored once in the shared ~/.config/mcp-google-auth/client.json (owner-only) and reused by every mcp-google-* server; tokens stay per-server. After this, call start_login.

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": {
      "path": "<path>"
    },
    "name": "set_client"
  }
}

Input Schema

Name	Required	Description	Default
`path`	Yes	Absolute path to the client_secret_*.json file downloaded from Google Cloud Console.

Schema Changelog

Changes observed during successful MCP inspections.

Addedv0.2.0Sep 20, 2026

TDQS

A4/5.0

Behavior4/5

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

Annotations indicate idempotentHint=true (safe to call again) and readOnlyHint=false (it's a write). The description adds valuable context: it stores the client once in a shared path, is reused by all mcp-google-* servers, and tokens stay per-server. It also warns against pasting secrets. This goes beyond annotation basics, though it does not mention any potential side effects like overwriting an old client.

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 three sentences, each earning its place: the first explains what and source, the second details storage scope, the third directs to start_login. The critical warning is naturally integrated. It is not overly verbose and the essential info is front-loaded.

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 single-parameter tool with no output schema, the description covers key operational aspects: the source file, the storage path, the security precaution, and the follow-up step. The only minor gap is the absence of error conditions (e.g., if the file is invalid), but that is acceptable given the simplicity.

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?

Schema description coverage is 100%, so the baseline is 3. The description reinforces that the path is to the JSON file and adds the explicit 'must never be pasted into the chat' security guideline. It doesn't add much beyond the schema, but the security note is valuable enough to nudge to 4.

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 specifies a clear verb ('saves') and resource ('OAuth client credentials from the JSON file') and adds detail about the source and storage location. It does not explicitly distinguish from siblings, but the uniqueness of this tool among the listed siblings is implicit given its specific task.

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?

It provides clear guidance on when to use the tool: after downloading the JSON file and before starting login. It also mentions the prerequisite of calling start_login after. However, it does not explicitly state when not to use it or mention alternatives, though none are obvious.

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