get_weight_trend

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

Annotations already mark it read-only and idempotent; the description adds meaningful behavioral detail beyond that: it only considers positive readings, rejects incomplete scans, and rejects inconsistent/missing/mixed unit codes. These details materially affect expectations.

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?

Three short sentences, front-loaded with the core purpose. The rejection behavior and disclaimer each add necessary context without 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?

The description is sufficient for a simple read-only summary tool with rich annotations. The main gap is that no output schema exists and the description does not specify the exact shape of the summary, though 'Summarize' and the tool name give reasonable grounding.

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?

The schema describes scaleUserId well and the description maps 'N days' to the days parameter. The description also adds unit semantics (native kg/lb/stone) that are not present in the schema. It does not deeply elaborate on days, but the name and bounds make it clear.

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 ('Summarize'), a specific resource ('positive weight readings over the past N days'), and supported units ('kg, lb, or stone'). It is clearly distinct from raw-data siblings like get_measurements and get_latest_measurement.

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 purpose is stated explicitly enough that an agent knows this is for weight summaries/trends rather than raw measurements. It does not name alternative tools, but the 'This is arithmetic, not medical advice' caveat clarifies a non-usage boundary.

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