things_complete_task

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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered; the description adds the concrete behavior that already-completed tasks are left as-is (no error, no re-write) and that completion status is read back. That is useful clarification beyond the idempotent hint, though return details remain thin.

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 short sentences, front-loaded with the core action and followed by the edge-case behavior; no 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 mutation with no output schema, the description covers the action and the no-op case, but omits what happens on a stale expected_modified_at and what the completion write actually changes, leaving a meaningful gap in an otherwise compact definition.

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 0% for 2 parameters, so the description must compensate. It only alludes to the required id ('one exact task ID') and says nothing about expected_modified_at, an optimistic-concurrency guard whose semantics an agent needs before calling.

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 ('Mark ... complete') and resource ('task ID'), plus the scope constraint 'one exact task ID', which cleanly separates it from things_create_task, things_update_task, things_move_task and things_schedule_task.

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?

The description implies usage by describing the completion effect and the already-complete case, but never states when to prefer this over things_update_task (which could also change status) or any prerequisites. Context is implied rather than explicit.

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