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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context beyond annotations: it details the calculation formulas, the 15-minute fall-asleep assumption, the cycle counts (6, 5, 4, 3), and the 'HH:MM' 24-hour time format. This is useful for setting expectations about the tool's output and logic.

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 tightly structured, starting with the core purpose, then detailing mode-specific behavior and formulas, and ending with time format and source. Every sentence contributes necessary information with no filler, making it efficient for an agent to parse quickly.

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 calculator with an output schema, the description fully covers the input modes, the formula used, the time format, and the cycle options. It leaves nothing essential unanswered; an agent has enough to invoke the tool correctly. The presence of an output schema means return-value details are handled elsewhere.

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 100%, so both parameters are already described in the schema. The description adds value by explicitly linking each parameter to its purpose in the formulas ('wake - 15 - cycles x 90...' and 'bedtime + 15 + cycles x 90...'), clarifying how 'mode' and 'time' interact. This goes beyond just restating 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 clearly states the tool's function with a specific verb ('Suggest sleep times') and resource, and immediately explains the two modes ('wake' and 'bedtime') with distinct formulas. This leaves no ambiguity about what the tool does or how it differs from the many sibling calculators, making it easily distinguishable.

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 explicitly explains when to use each mode: 'wake' for finding bedtimes from a wake time, and 'bedtime' for finding wake times from a bedtime. While it doesn't mention alternatives (there are none among siblings), the mode-specific guidance is clear and directly actionable for an agent.

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