get_daily_summaries

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

Goes well beyond the readOnlyHint/openWorldHint annotations: discloses the upstream endpoint, that long ranges are chunked into 365-day windows, the exact cap semantics ('must be P1Y or less': 365 passes, 366 is a 400), and that missing days are ABSENT rather than zero/null. That chunking and empty-vs-missing distinction is precisely the behavior an agent cannot derive from annotations.

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?

Front-loaded with the resource and metric list, then progressively technical detail. It is dense and every clause carries information, but the trailing sentence is truncated mid-thought ('Days with no data are ABSENT, not…'), signaling missing or awkwardly packaged 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?

With no output schema, the description does the work of explaining returns: unwrapped `data`, one object per day, grouped by named topics, typed from UserDailySummaryV2DTO. That is unusually complete for a read tool, though the cut-off sentence leaves the empty-day semantics unfinished.

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 start/end semantics and the YYYY-MM-DD (UTC) format are already documented in the schema. The description adds the date-span constraint but nothing new about the parameters themselves, 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+resource ('one whole-day summary per day') and enumerates exactly which metrics it bundles (steps, calories, heart rate, stress, Body Battery, SpO2), which distinguishes it from the many single-metric siblings like get_daily_steps or get_body_battery. An agent can tell this is the aggregate per-day read rather than a per-metric one.

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?

Usage context is implied through the year-cap and chunking behavior, which tells the agent how to invoke it for long ranges. However, it never explicitly contrasts itself with the many overlapping siblings (get_daily_stats, get_daily_steps, get_spo2_data), so the agent must infer when to pick this aggregate over them.

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