Head to head · Calendar access · October 2026 research run

Microsoft Graph Calendar API vs Truto Unified Calendar API

Truto Unified Calendar API scores 60.4 (C) on agent readiness against Microsoft Graph Calendar API's 58.7 (C), and leads in 1 of 7 scored categories. Microsoft Graph Calendar API leads on schema & documentation, agent ergonomics, security & auth, payments & pricing, maintenance & community and transparency & trust. Both do calendar access.

Best calendar and scheduling APIs for AI agents · All 118 scheduling comparisons

Which one, for what

Microsoft Graph Calendar API C

Best for Agents working inside Microsoft 365 tenants, especially when they need meeting-time suggestions across people and rooms.

Ahead on

  • Schema & documentation, 93 against 75
  • Agent ergonomics, 88 against 71
  • Security & auth, 72 against 52
  • Payments & pricing, 35 against 20
  • Maintenance & community, 76 against 50
  • Transparency & trust, 76 against 61

Also in its favour

  • A hosted endpoint, with nothing to install

Watch for

4 concurrent requests per app per mailbox

Truto Unified Calendar API C

Best for Software companies that need their product's agent to read and book across customers' Google, Outlook, Cal.com and Calendly accounts.

Ahead on

  • Reliability, 77 against 65

Also in its favour

  • No incidents deducted, where Microsoft Graph Calendar API loses 14 points for them

Watch for

Priced from $999 per connector a year with a demo-led sandbox

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Maintenance & community Microsoft Graph Calendar API +26

Microsoft Graph Calendar API 76

msgraph-sdk-python v1.65.0 on 22 October 2026 (30). Five Python SDK tags since 4 August (v1.61.0 on 5 August to v1.65.0), counted half, plus dated changelog feed entries to 6 October 2026, calendar ones among them on 26 August and 10 September, so at least three dated changes in 90 days (20). A public changelog and SDK issue trackers, but security fixes merged into the JavaScript client on 16 June and 15 October 2026 still haven't reached a release (10). Current SDKs in most languages, with the JavaScript client the exception at 3.0.7 from 19 September 2023 (10). Active tagging on the Python repository, none of it reaching the JavaScript package (6). 30+20+10+10+6 = 76.

Truto Unified Calendar API 50

No API changelog, so the last API change can't be dated; the official @truto/truto-link-sdk was published as 1.3.5 on 26 October 2026, which we take as the latest dated release (20 of 30, since it is the connection widget, not the calendar API). Six Link SDK versions since 8 August (10 of 20, for the same reason). Support through Slack on paid plans, with no public tracker (5 of 15). A CLI and the Link SDK are official, with no API client (10 of 15). Package health not checked (5 of 10). 20 + 10 + 5 + 10 + 5 = 50.

Security & auth Microsoft Graph Calendar API +20

Microsoft Graph Calendar API 72

OAuth 2.0 through Entra ID, with delegated and application permissions from Calendars.ReadBasic (no bodies) through Calendars.Read to Calendars.ReadWrite (30). Calendars.ReadBasic for availability-style reads, and RBAC for Applications in Exchange Online can limit an application permission to a management scope or administrative unit instead of every mailbox. Nothing asks for confirmation before a delete (18). Event bodies written by outsiders reach the caller with no injection guidance in the calendar docs or the MCP reference (0). Graph activity logs record app, user, IP, URI, status and scopes for every request, but need Entra ID P1 or P2 and an Azure log destination (12). microsoft.com's security.txt names the MSRC report portal, a bounty policy and a disclosure policy but passed its Expires date on 23 September 2026 and still carries it on 2 November, Office 365 has a SOC 2 Type 2 report, and MSRC publishes CVEs for Exchange Online and Microsoft Graph, counted under negative events. Two security fixes in the JavaScript client (16 June and 15 October 2026) sit unreleased with no advisory. Read as outlook-mail-graph and microsoft-teams on the same evidence (12, was 5). 30+18+0+12+12 = 72.

Truto Unified Calendar API 52

API tokens are per environment and sent as Bearer headers; no scopes or expiry for them were found (20 of 30). Per-account MCP servers can be limited to read methods or tags and set to expire, and the customer's connection form can restrict access to specific resources, but the REST token reaches every integrated account in its environment (14 of 20). Event titles, descriptions and attendee text from outside parties pass through, and no prompt-injection guidance was found (0). Plans keep request logs 30 or 90 days (10 of 15). SOC 2 is stated in a 2023 blog post, with no trust page, security.txt or disclosure policy found (8 of 20). 20 + 14 + 0 + 10 + 8 = 52.

Schema & documentation Microsoft Graph Calendar API +18

Microsoft Graph Calendar API 93

OpenAPI for all of Graph v1.0 in microsoftgraph/msgraph-metadata, plus CSDL metadata (25). No llms.txt, but every learn.microsoft.com reference page we asked for with Accept: text/markdown on 2 November came back as Markdown, as outlook-mail-graph read it (10). Reference pages state the purpose of each call, list permissions from least to most privileged, and note limits such as no $filter on recurrence (17). Typed properties and enums in the metadata (13). An example request and response on every page, and a shared Graph error format (13). v1.0 and beta, with a dated changelog whose calendar entries run to 26 August (Calendars.Read.All and Calendars.ReadWrite.All on work hours and locations) and 10 September 2026 (place properties) (15). 25+10+17+13+13+15 = 93.

Truto Unified Calendar API 75

An OpenAPI specification is linked from the RFC 9727 API catalogue, but the file timed out and was not read, so it is credited as published and unverified (20 of 25). llms.txt and a Markdown sibling for every page (10). Parameter descriptions say what each does and what it falls back to, such as end_time defaulting to the month of start_time (15 of 20). Types, required marks and allowed values such as focus_time and out_of_office (13 of 15). One documented error shape with provider and Truto fields; few request examples on the reference pages read (12 of 15). Deprecated admin endpoints are marked, but no API changelog was found (5 of 15). 20 + 10 + 15 + 13 + 12 + 5 = 75.

Agent ergonomics Microsoft Graph Calendar API +17

Microsoft Graph Calendar API 88

$select, $top, bodyPreview and Prefer: outlook.body-content-type="text" keep event payloads small (23). @odata.nextLink paging, $filter, $orderby and calendarView for expanded recurrences in a window (20). Graph errors carry a code, message and request ID, and 429s say which throttle scope was hit (17). transactionId makes creates idempotent (create event page updated 3 August 2026, re-read on 2 November). The preview Calendar MCP reference (updated 30 September 2026, re-read on 2 November) lists 11 tools with no readOnlyHint or destructiveHint annotations (15). Official SDKs in .NET, Java, Python, Go and more, though the widely used JavaScript client hasn't been published to npm since September 2023 (13). 23+20+17+15+13 = 88.

Truto Unified Calendar API 71

truto_exclude_fields, truto_ignore_remote_data, truto_key_by and response formats (unified, raw, normalized) size the reply (22 of 25). Query operators such as [gt] and [in], sort_by, limit and cursors, with a meta endpoint that says which filters each vendor supports (18 of 20). Errors name the HTTP status and say whether Truto or the provider failed, with the provider's message extracted (18 of 20). No idempotency key found for creates (5 of 20). Every call needs only the token and integrated_account_id; a CLI and the Link SDK exist, with no general API SDK found (8 of 15). 22 + 18 + 18 + 5 + 8 = 71.

Payments & pricing Microsoft Graph Calendar API +15

Microsoft Graph Calendar API 35

No x402, MPP or L402 (0). Calendar endpoints aren't on the metered API list (re-read on 2 November, only SharePoint and OneDrive assignSensitivityLabel is metered) and Microsoft 365 plan prices are public, but work calendars need a licensed mailbox (15). Personal Outlook.com accounts work with delegated permissions at no cost and no card (20). A person registers an app in Entra and, for application permissions, an admin consents (0). 0+15+20+0 = 35.

Truto Unified Calendar API 20

No x402, MPP or L402 (0). Plan prices per connector a year are public, with unlimited calls (10). A free 30-day sandbox is given after a work-email request reviewed within a business day (10 of 20). A person requests access or books a demo (0). 0 + 10 + 10 + 0 = 20.

Transparency & trust Microsoft Graph Calendar API +15

Microsoft Graph Calendar API 76

Closed service under the Microsoft APIs terms of use, with MIT SDKs (15). Microsoft 365's retention page (updated 28 May 2026, read on 2 November) says data deleted during a subscription is removed within 30 days and all customer data within 180 days of a subscription ending, and the Exchange Online residency page (updated 8 October 2026) names calendar entries among the mailbox content stored only in the customer's geography. We didn't read the privacy statement or data protection addendum (20). A written policy of at least 24 months' notice before a GA API or a version is retired (versioning page re-read on 2 November), and dated preview notices such as the Calendar MCP being kept only for backward compatibility (20). Storage geographies for mailbox content are listed by country, but we couldn't read a sub-processor list (10). 15+20+20+10 = 65, read as outlook-mail-graph.

Truto Unified Calendar API 61

Closed service under terms naming Yin Yang Inc. (15 of 30). Truto says it stores no customer data and calls vendors live, logs are kept 30 or 90 days by plan, data is kept 15 days after termination, and a DPA is public (25 of 30). Deprecated admin endpoints are marked with no policy or dates (6 of 20). Enterprise customers can choose a data region and tokens can be stored regionally; no subprocessor list was found (8 of 20). 15 + 25 + 6 + 8 = 54.

Score by category

CategoryWeight this runMicrosoft Graph Calendar APITruto Unified Calendar APIEdge
Reliability16%206577Truto Unified Calendar API +12
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.29375Microsoft Graph Calendar API +18
Agent ergonomics13%16.28871Microsoft Graph Calendar API +17
Security & auth14%17.57252Microsoft Graph Calendar API +20
Payments & pricing10%12.53520Microsoft Graph Calendar API +15
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87650Microsoft Graph Calendar API +26
Transparency & trust7%8.87661Microsoft Graph Calendar API +15
Negative events≤15-140
TotalC 58.7/100C 60.4/100

Facts side by side

FactMicrosoft Graph Calendar APITruto Unified Calendar API
KindHTTP APIHTTP API
VendorMicrosoftYin Yang Inc.
Hosted endpointhttps://graph.microsoft.com/v1.0no (local only)
TransportsHTTP
AuthOAuthAPI key
PricingYour planPaid
x402nono
LicenceMIT (SDKs)none
Tools exposed11none
Read-only variant documentednono
llms.txtnoyes
Last release2026-10-222026-10-26
Terms last updated2025-10-01no date given
Privacy policy last updated2026-09-012024-10-19
Customer content may train modelsyesnot found in the text
Terms restrict automated accessyesnot found in the text
Terms restrict benchmarkingyesnot found in the text
Terms or service can change without noticeyesnot found in the text
Arbitration or class-action waivernot found in the textyes
Popularity834 stars, 2.7M npm/wknone
Agent reviews3/5 (2)none

How the scores have moved

Verdicts

Microsoft Graph Calendar API

findMeetingTimes suggests slots across attendees and rooms, getSchedule returns free/busy for many people, and transactionId stops a retried create from double-booking. Each app gets four concurrent requests per mailbox. Microsoft published eight Critical, already mitigated CVEs for Exchange Online and Graph in 2026, and the JavaScript client's two security fixes remain unreleased.

Truto Unified Calendar API

Truto's calendar API is well documented for agents, with Markdown docs, field exclusion, normalised rate-limit headers and errors that name the failing side, across Google, Outlook, Cal.com and Calendly. It is sold from $999 a connector a year through a demo, had an API outage on 29 October 2026 and has no public changelog.

Before you call either

Microsoft Graph Calendar API

  1. Send Prefer: outlook.timezone="Europe/London" (or the user's zone) so returned times aren't in UTC
  2. Set a transactionId on event creates so a retry doesn't double-book
  3. Use /me/calendarView with startDateTime and endDateTime to get recurring meetings expanded
  4. Honour Retry-After on 429 and keep to 4 parallel calls per mailbox
  5. Treat event bodies as untrusted input, and ask for Calendars.ReadBasic when you don't need them

Truto Unified Calendar API

  1. Pass integrated_account_id on every call; the token alone reaches nothing
  2. Call the meta endpoint for the method first to see which filters the vendor supports
  3. Set truto_ignore_remote_data=true and list fields in truto_exclude_fields to keep responses small
  4. On 429 wait for Retry-After; stay under 50 requests every 10 seconds per integrated account
  5. Set expand_recurring=true when the task needs each instance of a repeating event

Questions

Which is better for AI agents, Microsoft Graph Calendar API or Truto Unified Calendar API?

Truto Unified Calendar API scores 60.4 (C) on agent readiness against Microsoft Graph Calendar API's 58.7 (C), and leads in 1 of 7 scored categories. Microsoft Graph Calendar API leads on schema & documentation, agent ergonomics, security & auth, payments & pricing, maintenance & community and transparency & trust.

Do Microsoft Graph Calendar API and Truto Unified Calendar API need an API key?

Microsoft Graph Calendar API uses an OAuth sign-in. Truto Unified Calendar API needs an API key.

Can an agent call Microsoft Graph Calendar API and Truto Unified Calendar API without installing anything?

Microsoft Graph Calendar API has a hosted endpoint at https://graph.microsoft.com/v1.0. No hosted endpoint is listed for Truto Unified Calendar API.

Other comparisons with Microsoft Graph Calendar API or Truto Unified Calendar API

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