calendar-mcp

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Book focus time

block_focus_time

Books the best available calendar slots as focus time until the required hours are filled, trimming the last block to fit. Use dry run to preview scheduled blocks before writing to the calendar.

Instructions

Book the best free blocks in a window as focus time, until the hours add up.

Takes the blocks find_focus_time would report, longest first, and creates an event on each until hours_needed is covered. The last block is trimmed to what is still needed rather than swallowing a whole afternoon. Events are created busy, with reminders off and without notifying anyone.

Run it with dry_run first when the user has not yet agreed to the times.

Args: time_min: Start of the window to book inside, ISO 8601. time_max: End of the window, ISO 8601. hours_needed: How many focus hours to book. title: Title for the blocks. Default 'Focus time'. calendar_id: Calendar to book on. Omit for the user's configured focus_calendar_id (see get_preferences). check_calendar_ids: Calendars whose events count as busy. Omit for every calendar the account has selected. description: Optional note to put in each block. dry_run: True to report the blocks that would be booked without writing anything to the calendar. account: Account name from 'calendar-mcp accounts'; omit for the default.

Input Schema

TableJSON Schema

Name	Required	Default
`title`	No	Focus time
`account`	No
`dry_run`	No
`time_max`	Yes
`time_min`	Yes
`calendar_id`	No
`description`	No
`hours_needed`	Yes
`check_calendar_ids`	No

Output Schema

TableJSON Schema

Name	Required	Description
`count`	No	Number of blocks.
`events`	No	The blocks, earliest first.
`dry_run`	No	True when nothing was written to the calendar.
`message`	No	One-line human-readable summary.
`time_max`	Yes	End of the searched window, ISO 8601.
`time_min`	Yes	Start of the searched window, ISO 8601.
`timezone`	Yes	Timezone the blocks are expressed in.
`satisfied`	No	True when hours_booked covers hours_needed.
`calendar_id`	Yes	Calendar the blocks were booked on.
`hours_booked`	No	Focus hours actually covered by these blocks.
`hours_needed`	No	Focus hours the caller asked for.
`total_free_hours`	No	Focus hours that were available in the window.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.1.0Sep 7, 2026

TDQS

A4.6/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, so the mutation behavior is somewhat disclosed. The description adds valuable detail: events are created busy, reminders off, no notifications, last block is trimmed to avoid over-booking, and dry_run avoids writing. This is meaningful behavioral context beyond annotations.

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?

The description is compact and front-loaded: the main behavior is stated in the first sentence, then algorithms, then side effects, then usage instruction, then parameter explanations. Every sentence adds information and there is no filler.

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?

Given 9 parameters, no schema-level descriptions, and an output schema, the description covers the core behavior and parameter semantics well. It doesn't describe the return value structure, but an output schema exists. It also leaves some details unstated, e.g., exact event timing or default calendar resolution, but references `get_preferences` for that. This is sufficient for an agent to select and invoke the tool correctly.

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 0%, so the description must compensate. It explains behaviorally what `time_min`, `time_max`, `hours_needed` mean, the meaning of `dry_run`, the effect of `calendar_id` omission, and `check_calendar_ids` as busy-blockers. It doesn't give exact format examples for ISO 8601 (though the schema type is string), but it adds enough meaning for most parameters.

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?

The description states a specific verb+resource: it books focus time by turning the best free blocks into calendar events. It also names the sibling tool `find_focus_time` as the source of the blocks, which differentiates it from other calendar creation tools like `create_event` or `quick_add_event`. The behavior is concretely described (longest first, trimming last block).

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?

The description explicitly tells the agent to run it with `dry_run` first when the user has not yet agreed to the times, and explains the relationship to `find_focus_time`. It also clarifies calendar defaults via `get_preferences` and account defaults via 'calendar-mcp accounts'. This gives clear when-to-use guidance and names related tools.

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