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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so safety behavior is covered. The description adds useful behavioral context by saying it returns 4-6 cycle recommendations based on 90-minute sleep cycles.

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 short and front-loaded with the core purpose. 'Use for sleep optimization' is filler and the list_bundles reference is tangential, but overall it remains efficient.

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 tool has full schema coverage, annotations, and an output schema, so much context is already structured. The description covers purpose and return summary, but it leaves the required-parameter ambiguity unresolved and provides no comparative usage guidance, which is a meaningful gap for this large calculator suite.

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 the schema already documents both parameters and their HH:MM format. However, the description says 'Inputs: target wake or bedtime,' which implies a single target input, while the schema requires both bedtime and wake_time; this ambiguity reduces clarity rather than adding meaning.

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 verb and resource: 'Estimate optimal bedtime or wake time based on 90-min sleep cycles.' It is clear what the tool computes, but it does not name or distinguish itself from any sleep-related sibling such as calculate_jet_lag_recovery.

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 guidance is limited to the vague phrase 'Use for sleep optimization,' with no when-to-use vs. alternatives, no exclusions, and no prerequisites. The note to see list_bundles is a cross-reference, not practical invocation guidance.

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