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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered structurally. The description adds genuinely new behavioral detail beyond that — notably that it returns today's session 'or the next one' when none exists today, plus the breadth of what is read. It does not discuss pagination or whether a partial day affects the response, so it stops just short of full disclosure.

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?

Two sentences, front-loaded with the usage trigger, followed by content scope and then the exclusion. Every clause carries information, though the long enumeration of returned data overlaps with the output schema and could be trimmed without loss.

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, the description need not explain return values, yet it still sketches them — helpful rather than harmful. Purpose, trigger, exclusion and account scoping are all present; the only untold nuance is how the 'next session' fallback is signaled in the response.

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 zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The description correctly implies a no-argument call scoped implicitly to 'today' in the user's account.

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?

The description uses a concrete verb and resource ('Reads today's session') and enumerates the scope of the payload: exercises, targets, logged sets, this week's sessions and volume, food and weight. It also explicitly names the sibling tools it is not (get_schedule, get_session), so an agent can distinguish it without opening a 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?

It states the triggering conditions ('when the person asks what's on today or how today's session is going, and before logging a set') and an explicit exclusion with the alternatives to use instead ('Do not use for another day's session; use get_schedule and get_session'). Both the when and the when-not are covered.

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