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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the write/mutating nature is covered structurally. The description adds only that the resulting state is 'completed (done)'; it omits whether the change is reversible (reopen_task exists), what happens to subtasks/checklists, and any permission 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?

A single short sentence with the action front-loaded and no filler. It is appropriately sized, though its brevity is partly the source of the missing context.

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 state-mutating tool with no output schema and an undocumented required parameter, the description leaves out permissions, reversibility, and side effects on related items. Annotations cover the safety profile, but the definition is still too thin to call the tool confidently.

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% — the single required parameter cardId is a bare string with no explanation. The description does not identify what cardId refers to (a task card identifier) or its expected format, so it fails to compensate for the schema gap.

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 specific verb ('Marks') and resource ('a task'), and clarifies the resulting state ('completed (done)'). It stops short of distinguishing itself from closely related siblings such as reopen_task, archive_task, or update_task, which an agent must infer.

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?

There is no guidance on when to use this rather than reopen_task (the inverse), archive_task, or update_task, nor any stated prerequisite such as the task existing or the caller having board membership. Usage must be inferred entirely from the name.

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