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

Beyond the readOnly/non-destructive annotations already present, it discloses the default window, that private activities are omitted (a real result-set constraint), and the critical interpretation caveat that an unlisted day is unknown rather than a day without the activity, plus that counts are days not times or amounts. These are exactly the traps an agent would otherwise fall into.

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-loaded with the resource and its scope, then the shape of the returned activity. Dense and mostly earned, though the `goal` field breakdown partly duplicates the output schema and could be trimmed if that schema is authoritative.

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?

Since an output schema exists, the description is not obliged to document return values, and it still covers privacy filtering, default range, and count semantics. The remaining gap is the ambiguity around the two date parameters, which leaves an agent guessing at boundary behavior.

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 0% — the two date params carry only format and null defaults, no descriptions. The description compensates partially by stating the default range (last 28 days), but never explains the semantics of a null date_from vs date_to or whether they're inclusive, leaving half the burden unmet.

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+resource (the user's own activities) and immediately scopes it against the obvious confusable: 'besides workouts (e.g. football, swimming, a drink)'. An agent can distinguish this from get_sessions/get_stats 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?

Gives clear context for use: activities rather than workouts, an explicit default range of the last 28 days, and the note that the user creates activities and goals in the AIm app. It stops short of naming an alternative tool or an explicit 'use X instead of get_goals' routing rule, so it's clear but not fully directive.

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