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

Annotations declare destructive/non-readonly/idempotent, but the description adds what those hints cannot: the cancellation is soft ("kept on record"), side effects are suppressed unless `notify` is true, the preview enumerates pass holders who would be notified, non-organizers are refused, and a personal connector token is required.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the purpose, then ordered by decision sequence (preview → confirm → identify session → permission → auth). It is dense to the point of being a run-on sentence chain, but each clause carries operational information rather than filler.

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

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

For a destructive, confirmation-gated mutation this covers everything an agent needs: the confirmation workflow, session identification, permission model, notification behavior, and credential requirement. Return values are partly described even though an output schema already exists, so nothing material is missing.

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

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

Schema coverage is 100%, so the schema already documents each parameter and sets a baseline of 3. The description goes further by explaining the cross-parameter contract — that `changeId` is produced by the preview and must be echoed with `confirm` — and by stating that `sessionId` and title are alternatives that can be disambiguated with time.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ("Cancels one session on the agenda of an event") plus the ownership scope ("the person organizes") and the resulting state ("marked cancelled and kept on record"). That last clause cleanly separates it from event_session_move and event_session_rename, which also act on session records.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives an explicit two-step protocol: first call without `confirm` to get a preview, read it back to the organizer, then re-call with `confirm: true` and the returned `changeId`. It also covers the ambiguity path ("on AMBIGUOUS or NO_SUCH_SESSION read the candidates back and ask") and the authorization failure path, leaving nothing to inference.

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