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

Beyond the annotations, the description discloses the specific fields that are modified and the conflict failure mode when the precondition is not met. This gives an agent concrete expectations about side effects and error behavior.

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 sentences with no filler: the action, the specific state changes, and the failure condition are all included. The most important behavioral detail is front-loaded.

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 single-parameter mutation with an output schema and annotations indicating it is neither read-only nor destructive, the description fully covers what the tool does, what it changes, and when it fails. Nothing essential 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?

The input schema already provides full coverage of the id parameter with a clear source reference. The description adds the meaningful precondition that the id must refer to a currently completed task, which is valuable semantic context for correct invocation.

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 ('Reopens') and a clear resource ('a completed task'), and states exactly what happens (clearing completion timestamp and completed-by user). This distinguishes it from the sibling complete_task without any ambiguity.

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 the tool is only for tasks that are currently completed, and explicitly notes that it fails with a conflict otherwise. It does not name sibling alternatives directly, but the context makes the appropriate use case obvious.

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