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

Annotations already establish that this is a safe, idempotent, non-destructive, non-open-world operation, so the bar is lower. The description adds genuinely useful non-annotation context: this is a UI action that opens a panel beside the conversation rather than returning data. It stops short of saying what the agent should do after the panel opens.

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?

A single sentence, front-loaded with the verb and the resource, with the scope clause doing useful work. No filler or redundancy.

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?

An output schema exists so return values need not be explained, and the tool takes zero required parameters, making it structurally simple. The description covers purpose and the UI-panel behavior adequately; only the post-open interaction model is unstated, which is a minor 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?

Schema description coverage is 100%, and the schema already documents date, babyId and timezone thoroughly (formats, defaults, fallback behavior). The description adds no parameter-level meaning beyond that, so the 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?

Specific verb ("Open") plus a concrete resource (a panel beside the conversation) and an explicit scope (logging feeds, sleep and nappies). An agent knows exactly what this does. It does not, however, distinguish itself from UI-oriented siblings like open_dashboard or show_day, which could plausibly be confused with it.

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?

Usage is implied by the stated purpose — call it when the user wants to log feeds, sleep or nappies — but there is no explicit when-to-use, no mention of when to prefer the data-mutating siblings (create_feed, create_sleep, create_nappy) instead, and no prerequisites stated.

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