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

Annotations already establish read-only, non-destructive, closed-world, so the bar is lower, yet the description still adds meaningful domain context: the fuel field's computation ('grams for the WHOLE session... raised when hard work follows, or your own number'), the distinction between target and targetDefault, and a pointer to control_signal. It stops short of describing pagination or failure behavior, so not a 5.

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 opening clause is well front-loaded, but the middle is a dense run-on with nested parentheticals (the fuel explanation spans multiple clauses and asides). Information density is high, yet the structure impedes scanning and some clauses could be split or trimmed.

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 must characterize the return, and it does so thoroughly: interval structure, raw blocks, totals, notes, target/targetDefault, control, and fuel composition. The main remaining gap is characterization of the 'date' input, but for a single-read tool this is largely complete.

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 0%, so the description carries the burden. It helpfully explains where iid comes from (get_plan / athlete snapshot) but adds nothing about what the required 'date' parameter means (scheduled date vs. day to read) or its interplay with iid. Half the parameters get meaning, so a middling 3.

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 ONE scheduled workout in full detail') and enumerates the payload scope (intervals, blocks, totals, target, control, fuel). An agent can immediately tell this apart from list-level siblings like get_plan or plan_workouts, and it names get_plan / the athlete snapshot as the source of the identifying iid.

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 clear context: 'Use the iid from get_plan / the athlete snapshot' and 'This is how you inspect exactly what the athlete is supposed to do before advising on or editing a session.' That is a concrete trigger. It stops short of explicit when-not or naming an alternative tool for other cases (e.g. catalog templates), so not a 5.

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