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

Annotations already declare readOnlyHint/openWorldHint/destructiveHint, but the description adds substantial context: it enumerates the returned fields (today's entry, PRS, confounder flags, baseline7d/28d, sd28d, zToday, rolling3d, n28), states 'Blocks computes NO verdict', and documents the house threshold rule (|zToday| ≥ 0.9, n28 ≥ 7). This is meaningfully more than the annotations provide.

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?

The description is a dense wall of run-on sentences and unexplained domain jargon (PRS, RHR, zToday, persist3d, h = round(baseline28d)) delivered in a single breathless block. It is over-stuffed and hard to parse rather than front-loaded and scannable.

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 carries the burden of describing return values, and it does so thoroughly by enumerating the entry fields and aggregates plus the scoring rules. An agent would know what comes back, even if the terminology is opaque.

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?

With 100% schema description coverage and a single parameter, the schema already documents `date` fully, and the description merely restates the default ('`date` defaults to the athlete's today'). No added syntax or format value 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?

States a specific resource ('the athlete's readiness picture for one morning') and scopes it to a single entry plus per-metric history aggregates, which separates it from a broad multi-day view. However, it never names the sibling tools (get_readiness, get_readiness_baseline) it most resembles, so the agent must infer the boundary between them.

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 description explains how to interpret output ('One morning is a reading; a shift that persists... is what moves a plan') but gives no explicit guidance on when to call this versus get_readiness or get_readiness_baseline. No prerequisites, no exclusions, no alternatives named.

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