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

Annotations already establish readOnly/destructive/openWorld, and the description adds substantial behavioral context beyond them: omitted dates are unbounded so a bare call returns the whole past and future calendar, days returned are only those with a session or note, `key:true` marks a KEY session declared in advance, and structure:true changes the payload shape. This is exactly the kind of cost/semantics disclosure annotations cannot carry.

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?

Purpose and scope are front-loaded, and with no output schema the dense return-value enumeration earns its space. However, the middle is a single run-on sentence with heavy parenthetical nesting that could be broken up for faster scanning, so it is informative but not maximally clean.

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?

There is no output schema, so the description carries the full burden of documenting the return payload, and it does: `days` contents, per-workout fields (iid, title, sport, zone, duration+TSS, goal, fuel, target, targetDefault, judge_by), day notes, monthlyTss, and the structure flag. Nothing an agent needs to call or interpret the result is missing.

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 the baseline is 3, but the description adds meaning the schema does not: both dates are inclusive, and omitting either makes that bound unbounded, with the extreme case spelled out. It also explains what structure:true actually produces (compact interval string) with a concrete example, exceeding the schema's terse 'include each workout's compact interval structure'.

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 what is already scheduled on the athlete's calendar') plus the scope ('in a date range'), and explicitly distinguishes itself from get_plan_workout ('for raw blocks of ONE entry use get_plan_workout'). An agent can route between get_plan, get_plan_workout and plan_workouts without opening any schema.

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?

Gives a clear purpose rationale ('so you don't double-book and can balance weekly load') and names one alternative with the condition that selects it (structure:true vs get_plan_workout). It lacks an explicit when-not statement or guidance on bounding the range for large calendars, so it falls just short of full routing guidance.

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