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

The description discloses the cost ($0.10) and API key requirement, which are relevant operational details. It does not contradict the annotations (readOnlyHint=false, destructiveHint=false) and adds context about the operation's side effects without being misleading.

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 concise, using a single sentence with a helpful example and cost note. Every part earns its place, and it avoids redundant wording.

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 logging tool, the description is adequate to understand the core purpose and cross-midnight handling. However, it omits explanations for optional parameters and does not clarify the output or error behavior, leaving some gaps for an agent invoking the tool.

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 only 36% (4 of 11 parameters described). The description implicitly references started_at and ended_at via the example but leaves notes, source, quality, timezones, idempotency keys, and other fields unexplained. Since coverage is low, the description should compensate but does not.

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 action (log) and the resource (sleep), and specifies it covers overnight and nap. It also provides a concrete cross-midnight example, distinguishing it from other log_* tools that handle different domains.

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?

It gives practical usage guidance via the cross-midnight example (14:00→03:00 = 13h / 780m), which clarifies how to handle overnight periods. However, it does not explicitly mention when to use this versus alternative tools like get_sleep or update_sleep, nor does it state any exclusions.

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