fitbit_activity

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

Annotations already declare readOnlyHint, destructiveHint=false, and openWorldHint, so the safety profile is covered. The description adds genuinely useful semantics beyond that: missing values are not zero (a real interpretation pitfall), the end date is exclusive, and a failed domain is surfaced explicitly rather than silently dropped.

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 dense sentences with the resource and range front-loaded and no filler. Terms like 'server-reconciled' and 'raw rollup fields' are compact but slightly jargon-heavy for an unprimed agent.

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?

With no output schema, the description reasonably explains what comes back (raw rollup fields), how to read missing data, and how failures appear. It does not address return shape, pagination, or units, which is the remaining gap for a data-fetch tool.

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 0%, so the description has to carry the burden, and it does partially: it defines the valid span (1-14 days) and that endDate is exclusive, which the bare regex pattern does not convey. It omits the YYYY-MM-DD format and whether the range is inclusive of startDate, leaving minor gaps.

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 resource (daily wearable activity) with its scope (1-14 civil days) and output character (raw rollup fields). It does not explicitly distinguish itself from siblings like fitbit_summary or fitbit_read, so the agent must infer which one to pick.

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 1-14 day limit and end-exclusive semantics imply the valid usage envelope, but there is no explicit when-to-use guidance or named alternative such as fitbit_summary or fitbit_compare. Usage is only inferable from the constraints given.

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