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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is known; the description adds genuinely new behavior: partial-post cancels affect only still-scheduled channels, the task remains on the plan, and cancelledOn records where it landed. It also notes a prerequisite ("It needs an act key"), though that term is unexplained and no such parameter exists in the schema, leaving ambiguity about what the agent must supply.

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?

Five short sentences, front-loaded with the action and followed by constraints and the alternative tool. The parenthetical "(cancelledOn says where)" and the dangling "It needs an act key" are slightly fragmented, but there is very little wasted text.

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 mutation with no output schema, the description covers preconditions, partial-failure semantics, and where the cancellation is recorded, which is substantial. It omits reversibility (whether a cancelled row can be restored, e.g. via work_reschedule) and leaves the "act key" requirement unresolved, both of which matter for a destructive tool.

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 description coverage is 100%, so id, reason, and project are already documented, and the description largely restates them ("Say why in plain words; the owner reads it"). The mention of an "act key" requirement implies an input concept that is absent from the schema, which is more confusing than clarifying. Baseline 3 applies since the schema carries the parameter burden.

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?

The description states a concrete action and object: taking a scheduled work row ("task") off the week and cancelling it. It also distinguishes the behavior from slot_drop (later-day slots) and from a full cancel when a post has partially gone live. The phrasing "take a task off the week" is informal and never uses the word "cancel" for the primary resource type, so it stops just short of a crisp verb+resource statement.

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?

It gives an explicit applicability gate ("Only rows that have not gone live") and routes one adjacent case to an alternative tool ("A slot on a later day comes off with slot_drop"). It does not address overlap with other nearby siblings such as scheduled_posts_remove, set_aside, or work_reschedule, so the guidance is clear but not exhaustive.

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