get_body_battery

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

No annotations exist, so the description must carry full burden. It only describes return content (levels, charge/drain) but omits behavioral details: authentication needs, read-only nature, rate limits, error handling for invalid periods, or whether data is aggregated daily. The presence of an output schema partially offsets the need to describe return format, but behavioral context is insufficient.

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 extremely concise: two sentences plus a short Args block. Every word adds value. The main purpose is front-loaded, and the parameter explanation is immediately appended. No filler or redundancy.

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 tool with one optional parameter and an output schema, the description provides a basic understanding: what the metric is and how to specify the period. However, it lacks units (e.g., is it a percentage?), range, and explicit documentation of returned fields. The output schema likely covers structure, but an agent could still be uncertain about interpreting results.

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 0% (no parameter description in schema). The description compensates well with concrete examples: 'last 7 days', 'this week', '2026-08-01 to 2026-08-18'. This adds explicit format guidance beyond the schema's type and default. However, it could further clarify timezone handling or accepted date formats.

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 retrieves 'Body Battery energy levels' and explains what it shows (charged and drained each day) and what higher values mean. This specific verb+resource combination distinguishes it from sibling tools like get_heart_rate or get_sleep, which cover different metrics.

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 an example for the period parameter but gives no guidance on when to choose this tool over alternatives, no prerequisites, and no context like 'use this for daily energy trend analysis'. An agent would lack direction for appropriate invocation.

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