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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real value beyond that: the values are *calculated* from recent workouts over fixed 7-day and 28-day windows, and it carries an explicit scope disclaimer ('fitness information, not a medical assessment') that bounds how an agent should present the result.

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?

One tightly packed sentence plus one short scope clause. The core resource and its metrics are front-loaded, and every phrase (acute vs chronic, ratio, trends, non-medical) contributes 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?

With no output schema, the description usefully enumerates what comes back — acute load, chronic load, ratio, trends — which is enough for an agent to know what to do with the result. It stops short of saying the units, whether trends are a time series or a single delta, or how it behaves when fewer than 28 days of history exist.

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?

The tool takes no parameters, so there is nothing for the description to disambiguate; baseline for zero-param tools applies. No misleading hints about hidden arguments are present.

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 calculated training load and readiness from recent workouts') and then pins down the exact metrics: seven-day acute load, 28-day chronic load, their ratio and trends. That level of specificity separates it from generic siblings like get_daily_metrics or get_week_summary, though no sibling is named explicitly.

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 is implied by the metric definition rather than stated: an agent can infer it applies to fitness-progression questions, not raw activity listings. There is no explicit when-to-use clause and no routing to an alternative such as get_daily_metrics for underlying day-level data.

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