Read a body size history

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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is settled. The description adds real behavioral context beyond that: values are in the user's size unit (cm unless the app setting is changed), fat_percentage is in %, days with no measurement are omitted (sparse series), and results are ordered newest first. It does not mention pagination boundaries beyond the limit cap, which holds it just short of 5.

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?

Purpose and output shape are front-loaded in the first clause, and every sentence carries required information about units, omissions, or date semantics. The middle sentences are dense with semicolon-chained conditionals, which costs some readability, but there is no filler.

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?

An output schema exists, so return values need no explanation, and the annotations cover the safety profile. Combined with the unit conventions, sparse-day behavior, date defaults and sibling routing, an agent has everything needed to call this correctly.

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 100%, so the baseline is 3 and the schema already documents all four parameters including formats and defaults. The description goes beyond the schema by explaining the interaction between from_date, to_date and limit (default range end, fallback to newest-N when undated), which is semantics the schema alone does not convey.

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 and resource ('List the logged values of one body measurement'), gives the return shape {date, value} and ordering (newest first). It explicitly differentiates itself from the two closest siblings, get_body_measurements and get_weight_history, so an agent can route without opening any schema.

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?

Gives explicit conditional behavior for from_date/to_date/limit ('without to_date it stops at today, so give it for later days; without either it lists the newest entries up to limit') and names the alternatives with the condition that selects them ('first and last value of every part over a period is get_body_measurements'). Both when-to-use and when-to-use-something-else are covered.

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