calendar-mcp

Overview Schema Source Related Servers Discussions Admin

Suggest better times for an event

suggest_reschedule

Idempotent

Suggest better times for an existing meeting by analyzing calendar availability and ranking options by attendee conflicts, with an option to apply the best suggestion.

Instructions

Propose better times for an existing meeting, ranked, keeping its length.

Reads the event, then looks for slots of the same duration inside the user's working hours where the organiser is free, and ranks them: fewest attendee conflicts first, the event's current day next, then earliest. Slots that sit closer to another meeting than the user's buffer allows are penalised, not hidden.

Read-only by default -- it suggests, the user decides. Set apply to move the event to the top suggestion once they have agreed to it.

Args: event_id: The event to reschedule (from find_events). calendar_id: Calendar the event lives on. search_days: How many days ahead to search. Default 7, maximum 60. max_suggestions: How many times to propose. Default 5, maximum 20. search_from: Start searching from this time, ISO 8601. Defaults to now. apply: True to actually move the event to the best suggestion. Only set this when the user has agreed to the time. account: Account name from 'calendar-mcp accounts'; omit for the default.

Input Schema

TableJSON Schema

Name	Required	Default
`apply`	No
`account`	No
`event_id`	Yes
`calendar_id`	No	primary
`search_days`	No
`search_from`	No
`max_suggestions`	No

Output Schema

TableJSON Schema

Name	Required	Description
`count`	No	Number of suggestions returned.
`applied`	No	True when the event was actually moved.
`message`	No	One-line human-readable summary.
`summary`	No	Event title.
`event_id`	Yes	Event the suggestions are for.
`timezone`	Yes	Timezone the suggestions are expressed in.
`attendees`	No	Attendee calendars whose availability was checked.
`calendar_id`	Yes	Calendar the event lives on.
`current_end`	No	Current end, ISO 8601.
`suggestions`	No	Proposed times, best first.
`applied_event`	No	The event after the move; null unless 'applied' is true.
`current_start`	No	Where the event sits now, ISO 8601.
`search_time_max`	Yes	End of the searched window, ISO 8601.
`search_time_min`	Yes	Start of the searched window, ISO 8601.
`duration_minutes`	No	Length of the event, preserved by every suggestion.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.1.0Sep 7, 2026

TDQS

A4.8/5.0

Behavior5/5

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

The description goes well beyond annotations by disclosing the ranking logic, the buffer penalty behavior, and the conditional side effect: 'Read-only by default' with `apply` performing the actual move. It also distinguishes between suggesting and acting, which is exactly the behavioral nuance an agent needs.

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 organized into a summary, a behavior explanation, a side-effect warning, and a clear Args block. Every sentence contributes meaningful information without repetition or filler, making it easy for an agent to parse quickly.

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?

For a 7-parameter scheduling tool, the description covers algorithm, ranking criteria, working-hours behavior, side-effect conditions, defaults, and parameter semantics. Since an output schema exists, return values do not need to be described. No critical usage context appears to be missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, and the description fully compensates by explaining every parameter's purpose, defaults, and constraints. It even provides cross-tool context like 'from `find_events`' and account sourcing from 'calendar-mcp accounts', which is far more useful than the bare 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?

The first sentence states a specific verb and resource: 'Propose better times for an existing meeting, ranked, keeping its length.' This clearly separates it from tools like move_event, find_focus_time, or update_event. The description also clarifies that it reads and suggests rather than directly mutates, making the tool's role unmistakable.

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?

The description explains when to use the tool: for an existing meeting, searching within working hours, and only applying the change after the user agrees. It does not explicitly name sibling alternatives or state when NOT to use it, but it gives strong contextual guidance and warns about setting `apply`.

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