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

Annotations already indicate readOnlyHint=false, destructiveHint=false, and idempotentHint=true, covering the safety profile. The description adds only the ability to set done to true or false, which is minor additional behavioral context beyond what annotations provide. No contradiction is present.

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 efficient sentences that front-load the action and include the essential toggle behavior and item_id source. Every word 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?

This is a simple write tool with 80% schema coverage, safety annotations, and no output schema. The description covers the core behavior and data source. It does not detail error conditions or the response format, but given the annotations and parameter descriptions, the agent has enough to call it 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?

Schema coverage is 80% (4 of 5 parameters described), with the 'done' parameter lacking a schema description. The description compensates by explicitly explaining its true/false semantics. It also reinforces that item_id comes from get_checklist, adding value beyond the schema.

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 ('Mark'), a specific resource ('checklist item'), and the two states it can set (done: true / done: false). It is clearly distinguishable from sibling tools like add_checklist_item (adds) or get_checklist (reads).

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 gives clear context for when to use the tool: to toggle an item's done state. It also tells the agent to source item_id from get_checklist, which is a helpful usage hint. However, it does not explicitly name alternatives or situations where this tool should not be used.

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