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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so safety is covered. The description adds genuinely useful context the annotations lack: the payload contents (high-stress and recovery seconds) and the requirement that the date be the user's LOCAL date rather than UTC, a real source of off-by-one errors.

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, zero filler, with the what and the how-to-call-it front-loaded. Nothing could be removed without losing information.

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, read-only metric fetch with no output schema, the description discloses enough: what is measured, in what unit-framed terms, and which calendar the date follows. Minor gaps remain around behavior when no data exists for a date (empty vs error), but overall it is sufficient to call correctly.

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% and the date parameter already carries the pattern and local-date note, so the description largely repeats structured data. The emphasis on 'strict YYYY-MM-DD' and LOCAL is a mild reinforcement but adds no new syntax or meaning.

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?

Names a specific verb (get) and resource (daily stress metrics) and even enumerates the returned measures: high-stress and recovery seconds. It does not, however, distinguish itself from adjacent siblings like get_resilience or get_daily_summary, which also touch stress/recovery data.

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 second sentence only gives the parameter format, not when to choose this over get_daily_summary, get_resilience, or get_date_range. There is no stated prerequisite or exclusion, leaving usage to inference from the tool name.

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