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

Annotations already indicate this is a non-read-only, non-idempotent mutation. The description adds valuable behavioral context by explaining that a required step blocks sign-off while an optional one does not, and by noting the returned id. It does not mention duplicate creation on repeated calls, but the idempotentHint=false annotation already covers non-idempotency.

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 sentences with no wasted words. It front-loads the primary action and return value, then adds the key business rule about required steps. It is easy to scan and fully relevant.

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?

The description covers the core return value and the most important behavioral consequence (sign-off blocking). It does not describe the exact output shape or error conditions, but the schema covers parameter details and the annotations cover mutation/idempotency, making this reasonably complete for an add-item tool.

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 100%, so the schema fully documents all six parameters. The description only loosely references text, section heading, and required status without adding meaning beyond the schema, so the baseline 3 is appropriate.

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 action ('Add one step to a checklist') and names the concrete resource and return value (an I01-style id). It is clearly distinct from siblings like checklist_item_remove and checklist_create.

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 says what the tool does but does not provide when-to-use guidance, exclusions, or alternatives. It never mentions that removing a step should use checklist_item_remove or that checklist_create is for creating a new checklist.

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