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

Annotations already convey that the operation is not read-only and not destructive, so the description does not need to restate those facts. It adds useful behavioral context by clarifying that this creates a new attachment on an existing task or plan rather than modifying an existing one. Additional details such as idempotency or exact mutation behavior are not necessary given the annotation coverage.

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 only two sentences and every part contributes: the first sentence gives the trigger and scope, the second gives a clear exclusion. No fluff, repetition, or unnecessary background material is present.

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?

Given the 100% schema coverage, the output schema, and the non-read-only/non-destructive annotations, the description provides enough decision context for correct tool selection and invocation. It could be slightly richer by naming the editing alternative explicitly, but the existing wording is sufficient to avoid the main confusion with update_list_attachment.

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 parameters are already documented in the schema itself. The description adds general context about attaching lists to existing tasks or plans, but it does not need to restate parameter meanings. This aligns with the baseline of 3 when the schema carries the detailed parameter documentation.

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 has a clear verb ('add') and resource ('list attachment to an existing Familia task or plan'), and it enumerates concrete use cases: checklist, shopping list, packing list, or structured subtasks. It also explicitly rules out editing an existing attachment, which distinguishes it from update_list_attachment without needing to open the schema.

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 states when to use the tool ('when the user asks to add a new checklist, shopping list, packing list, or structured subtasks to an existing Familia task or plan') and provides a direct exclusion ('Do not use for editing an existing attachment'). It stops short of naming sibling alternatives like update_list_attachment or create_list_task explicitly, but the 'existing' and 'do not use for editing' cues are strong enough for routing.

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