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

With no annotations supplied, the description carries the full behavioral burden and does add real value: it discloses the API-key/auth requirement and the non-obvious side effect that status and progress are set together by one rule. It stops short of stating what happens on an already-completed task (idempotency), whether a failure is returned for an invalid or already-done taskId, or what the response contains.

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?

Three short sentences, front-loaded with the action and followed by the constraint and the warning; every sentence carries information. Slightly clunky phrasing ('sets both through the same rule the app uses') but 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 single-parameter mutation with no output schema, the description covers the essentials: what it does, the auth prerequisite, the coupled side effect, and the correct alternative. Only failure/idempotency behavior is left implicit, which is a modest gap.

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?

Only one parameter (taskId) exists and schema description coverage is 100%, with the schema already telling the agent where the id comes from (list_tasks). The description adds no format, constraint, or edge-case meaning about taskId, so the baseline of 3 applies.

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 and resource ('Mark one task done') and scopes it to the connected LoopGantt account, so it is immediately distinguishable from the generic update_task sibling.

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 gives explicit routing guidance: use this tool to complete a task, and do NOT use update_task to set progress to 100 in the hope that status follows. That is a named alternative plus the condition that excludes it.

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