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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real behavioral value by disclosing the fixed 5-hour half-life assumption that governs the accuracy of the result, plus the shape of the output (remaining mg and clearance forecast). It does not mention that individual variation, smoking, or medication alter clearance, which is the main caveat for this kind of estimate.

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?

Four short sentences, front-loaded with what is computed, then usage, then inputs/outputs, then a related-tool pointer. Nothing is padded, though the inputs/outputs sentence is largely redundant given the schema and output schema.

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 two-parameter, low-complexity calculation with a full schema and an output schema, the description supplies the model assumption and the intended use, which is enough to call it correctly. Missing caveats about half-life variability are a minor gap rather than a blocker.

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 both parameters carry their own descriptions, so the schema does the heavy lifting. The description's 'Inputs: caffeine mg, time since intake' merely restates them without adding units, ranges, or edge-case handling beyond 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?

States a specific verb (Compute) and resource (remaining caffeine in body over time) and names the underlying model (5-hour half-life), which is more than a restatement of the title. However, it does not distinguish itself from the closely related siblings calculate_caffeine_half_life and calculate_caffeine_intake, which an agent could easily confuse 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?

'Use for sleep planning' implies a context but gives no when-not guidance and names no alternative among the three caffeine-related siblings. The pointer to list_bundles is a discovery hint, not selection guidance.

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