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

With no annotations, the description carries full burden. It explains that real-world charging losses (80-90% efficient) are accounted for, outputs include time in hours/minutes, energy in Wh, and C-rate for safety. It also mentions chaining from solar_sizing. It does not contradict annotations and provides useful behavioral context.

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 efficient, with about 5 sentences front-loading the primary function, then outputs, use cases, and safety note. Every sentence adds value; no fluff. Slightly longer than necessary, but not wasteful.

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?

Given the presence of an output schema (from context signals), the description focuses on what matters: inputs, calculations, use cases, and safety. It covers all necessary aspects for a calculation tool of moderate complexity.

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%, so baseline is 3. The description adds context (e.g., 'typically 80-90% efficient' for efficiency parameter) but does not significantly enhance meaning beyond schema descriptions. It mentions outputs like C-rate which tie to parameters, but that's not direct parameter semantics.

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 'Estimates battery charge time given capacity in mAh, charge current in mA, charger efficiency, and initial state of charge.' It lists specific outputs (time, energy, C-rate) and distinguishes from sibling tools like battery_autonomy and mah_to_wh by mentioning specific use cases like solar sizing and EV planning.

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 provides explicit use cases: 'solar charge controller sizing, USB charging time estimation, lead-acid float charging, and EV battery planning.' It also notes safety guidelines for C-rate. However, it does not explicitly state when not to use this tool or provide alternatives, which prevents a 5.

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