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

Annotations already declare readOnlyHint=true, so the safety profile is covered externally. The description adds only the REST endpoint mapping, which is useful for orientation but does not disclose return shape, pagination, or rate-limit behavior beyond what the annotation implies.

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?

Two tight sentences with the data description front-loaded and the REST reference trailing. Every clause is relevant, though the REST path adds marginal value for an agent that cannot call HTTP directly.

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 read-only, single-enum-parameter tool with no output schema, the description gives enough to select and invoke it correctly. The only real gap is the absence of routing guidance against the many sibling activity tools.

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?

Sole parameter 'period' is fully documented in the schema (100% coverage) including its enum values, so the schema does the heavy lifting. The description merely restates 'daily or weekly period' and adds no syntax or format detail beyond the schema.

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 names the specific resource (the user's activity goals) and enumerates the goal types (steps/distance/calories/active-minutes) and periods, so an agent knows exactly what data comes back. It is clear, though it does not explicitly contrast itself with neighbors like fitbit_daily_activity_summary or the time-series tools.

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?

There is no when-to-use guidance and no mention of alternatives, despite a crowded sibling set of activity-related tools. Usage is only implied by the resource description, which leaves the agent to infer when this beats fitbit_daily_activity_summary.

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