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

The description aligns with annotations: destructiveHint=true and readOnlyHint=false confirm this is a mutating, destructive operation. The description adds the nuance that the target must be an existing plan item and that deletion should only happen on explicit user request, but it does not disclose additional behavioral details such as irreversibility or side effects. Since annotations already cover the destructive nature, a 3 is appropriate.

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 concise sentences with no filler. The critical usage condition is front-loaded, and the differentiation from the sibling tool is packed into a short second sentence. 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?

For a simple two-parameter mutation tool with 100% schema coverage, a destructive Hint annotation, an output schema, and explicit sibling routing, the description is complete. An agent has enough information to select the tool, populate the required planItemId, and understand the destructive nature of the operation.

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 already documents both timezone and planItemId. The description reinforces that planItemId refers to an existing plan item, but this is a minor addition; the parameter semantics are carried by the schema. Baseline 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 uses specific verbs ('delete, remove, or cancel') tied to a clear resource ('existing Familia plan item'), making the tool's purpose unmistakable. It also differentiates from the sibling familia_update_plan by explicitly stating what this tool is not for.

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 first sentence states exactly when to use the tool: only when the user explicitly asks to delete, remove, or cancel an existing Familia plan item. The second sentence names the alternative (familia_update_plan) and the conditions that should route to it, providing excellent when-to-use and when-not-to-use guidance.

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