get_fitness_age

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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description's only added claim is that date restrictions follow the official interface, but those restrictions are never stated — a vague pointer, not disclosed behavior. No mention of missing-data behavior or return shape.

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?

It is short, but the content is split across Chinese and English sentences that partly repeat each other, and the deferral clause is filler rather than signal. The key fact (return fitness age for a date) is present but not front-loaded.

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 single-parameter tool with no output schema and zero schema description coverage, the description must at minimum explain the date format and any range limits. Instead it offloads both to an external 'official interface' the agent cannot consult, leaving the call under-specified.

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%: the single required parameter calendar_date has no format, timezone, or range guidance anywhere. The description says parameters 'follow the official interface', which leaves the agent with nothing concrete about how to format the date string.

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 English sentence 'Return fitness age data for a calendar date' names a specific verb and resource, and the topic clearly separates it from siblings like get_daily_steps or get_daily_sleep. The Chinese lead-in and 'one-to-one with the official client' note add identity but no additional specificity.

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?

Nothing tells the agent when to call this versus other daily-metric tools, nor what to do when data is missing. The only guidance is a deferral to unspecified official API rules ('日期限制沿用官方接口'), which the agent cannot act on.

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