Mark Planner Item Done

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

Annotations already declare readOnlyHint=false, idempotentHint=true and destructiveHint=false, so the safety profile is partly covered. The description adds genuinely new scope information: the change is confined to the caller's own To Do list and has no submission side effect — valuable given openWorldHint=true, which could otherwise suggest broader effects. It stops short of describing what the response contains or whether the item disappears from the list.

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?

Two tight sentences with zero filler. The primary action is front-loaded and the side-effect disclaimer follows immediately where it is most useful.

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 3-parameter, no-output-schema state-toggle tool, the description covers the action, the scope of effect, and the non-submission guarantee. Minor gaps remain around what is returned and whether the item vanishes from list_planner_items, but nothing essential to calling it correctly 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 description coverage is 100%, with the enum values and the done default fully documented in the schema itself. The description only conveys the toggle semantics already implied by "(or back on)"; it adds no format or sourcing detail beyond what the schema provides. Baseline 3 applies.

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+resource combination ("Check an item off ... your Canvas To Do list") and covers both directions of the toggle. It also preempts confusion with submission tools by noting it does not submit anything. It does not differentiate itself from close siblings like dismiss_planner_item or mark_module_item_done.

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?

Useful implied guidance: the parenthetical "(or back on)" plus the schema's default make clear this is the tool for toggling completion state. The explicit "does not submit anything" sets a boundary against submit_assignment_* tools. However, it never names an alternative or says when to prefer dismiss_planner_item or mark_module_item_done instead.

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