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

The annotations already indicate this is not read-only and not destructive, and the description builds on that by disclosing the side effect of recording momentum stats and the conflict failure mode for already-completed tasks. This adds useful behavioral detail beyond the structured annotations, though it does not describe output details or authorization requirements.

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?

The description is two concise sentences with no filler. The primary purpose is front-loaded, and the error condition is stated separately and clearly. Every sentence earns its place.

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 simple one-parameter tool with a full output schema and clear annotations, the description covers purpose, side effects, and failure behavior. Nothing essential is missing for an agent to select and invoke the tool correctly.

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?

The schema already fully documents the single 'id' parameter with a clear description ('Task id from create_task or list_tasks'), so the parameter burden is mostly carried by the schema. The description reinforces that the parameter refers to a task but adds no new parameter-level meaning beyond what the schema provides.

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 clearly states the specific action ('Marks a task as completed') and the resource affected (a task), and adds meaningful context about recording completion for household momentum stats. It also distinguishes this tool from siblings like uncomplete_task by describing the completion state change explicitly.

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 clearly implies when to use this tool: to complete an open task. The conflict note also tells the agent not to call it on already-completed tasks, which is useful usage guidance. However, it does not explicitly name alternatives such as uncomplete_task or update_task, so the guidance is clear but not fully explicit.

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