get_recent_metrics

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

Annotations already declare read-only, idempotent and non-destructive behavior. The description adds genuinely new semantics: metric isolation means unsupported types degrade gracefully rather than failing the whole response, which an agent cannot infer from annotations or schema.

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 short sentences with the scope stated first and the failure-isolation caveat second; no filler. Slightly compressed to the point that the default-range point and the isolation point are the only content.

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?

Adequate for a 7-parameter read tool with full schema coverage and safety annotations, but with no output schema the description says nothing about the response shape or granularity, and it leaves the sibling-selection question entirely open.

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 100%, so every parameter is already documented with defaults, bounds and enums. The description only restates the 7-day default and adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 ('Read recent Fitbit metrics') plus a scope ('safe default 7-day range'). It does not differentiate from siblings like get_metrics, get_health_snapshot, or get_trends, and the 'Fitbit' framing is slightly at odds with the HEALTH_KIT source option.

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?

No indication of when to prefer this over get_metrics, get_health_snapshot, get_trends, or get_daily_summary, despite a very crowded sibling set. 'Recent' plus the 7-day default only weakly implies a contextual use case.

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