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

Annotations already cover the read-only and destructive hints, so the safety profile is known. The description adds that the task is closed and where to get the task_id, but does not disclose any additional side effects or error behavior. This is adequate but not rich beyond annotations.

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: the first states the action, the second states the input source. There is no filler or unnecessary detail.

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 one-parameter mutation with annotations and an output schema, the description is sufficient to guide invocation. It could mention what happens on invalid task IDs or whether the action is reversible, but these are not required for basic usage.

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 documents task_id with 100% coverage. The description adds value by specifying the provenance of the task_id ('from todoist_list_tasks'), which helps the agent correctly populate the parameter. This exceeds the baseline for schema-only coverage.

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 uses a specific verb ('Mark') and resource ('Todoist task complete'), and clarifies what 'complete' means ('closes it'). It also tells the agent to pass a task_id from todoist_list_tasks, which distinguishes it from other completion tools like complete_reminder.

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 clearly states the context for use: marking a Todoist task complete, and provides the necessary prerequisite of using a task_id obtained from todoist_list_tasks. It does not explicitly name alternative tools or state when not to use it, but the usage context is clear and actionable.

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