@mnicole-dev/calcom-mcp-server

get-busy-times

Retrieve busy time blocks from connected calendars for a specified date range to identify availability conflicts and open slots.

Instructions

Get busy time blocks from connected calendars.

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": {
      "dateFrom": "<dateFrom>",
      "dateTo": "<dateTo>"
    },
    "name": "get-busy-times"
  }
}

Input Schema

Name	Required	Description
`dateTo`	Yes	ISO 8601 end date (e.g. 2024-09-07T23:59:59Z)
`dateFrom`	Yes	ISO 8601 start date (e.g. 2024-09-01T00:00:00Z)
`calendarsToLoad`	No	Specific calendars to load (defaults to all)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Aug 30, 2026

TDQS

C2.9/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only restates the operation and source without mentioning timezone handling, default calendar behavior, potential errors, or whether this is a safe read operation.

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 a single, front-loaded sentence with no redundant wording. It is appropriately concise, though the brevity comes at the expense of usage and behavioral context.

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

Completeness3/5

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

For a simple read-only lookup with complete schema coverage, the description gives the core idea but lacks output-shape details and sibling relationships. Since there are no annotations and no output schema, the agent has limited context beyond the schema.

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%, with all three parameters already described with types, required flags, and defaults. The description adds no additional parameter semantics beyond what the schema already provides.

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 uses a specific verb ('Get'), a specific resource ('busy time blocks'), and a source ('connected calendars'), making the tool's core function clear. It is distinguishable from siblings like get-available-slots, though it does not explicitly contrast with any sibling.

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?

No guidance is given for when to use this tool versus alternatives such as get-available-slots, list-calendars, or list-bookings. There is no mention of scheduling workflows, prerequisites, or exclusion criteria.

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