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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety bar is low. The description adds genuinely useful behavior: the summary/full payload distinction (implied cost of detail='full'), the 30-day default window, and the 100-result cap. It does not mention auth or rate limits, but those are minor against the annotation coverage.

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?

Front-loads purpose in the first sentence, then the detail-mode semantics, then the args list — a sensible order with no wasted prose. The Args block is redundant with a 100%-covered schema, which is the only structural inefficiency.

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 an output schema present, return values need not be explained, and the description covers date defaults, the result cap, filtering, and the summary/full tradeoff. An agent has enough to call it correctly; only explicit sibling routing 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 description coverage is 100%, so the schema already documents all five parameters and the baseline is 3. The description largely restates the same fields and defaults; its only modest addition is enumerating the fields returned under each detail mode, which is not parameter-level syntax the schema lacks.

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 — 'Get completed workout sessions' — and the detail-mode elaboration (name/date/duration/sets) makes the payload scope concrete. It doesn't explicitly name which sibling to use instead (get_workout_detail, get_exercise_history), leaving differentiation to inference from the resource phrase.

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 implies context through date-range defaults and a workout_name filter, and explains what the detail modes yield, which helps choose a mode. But there is no explicit when-to-use/when-not guidance or naming of alternatives among the many get_* siblings.

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