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

Goes well past the annotations: full-day replace (not merge), no undo, throws GarminError when no optional field is supplied, and the load-bearing distinction between notes: undefined (preserve) and notes: "" (clear). These are exactly the behavioral facts an agent cannot derive from destructiveHint/openWorldHint alone.

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 core action, then constraints, then the safety warning. Dense and every clause carries information, though the bolding/backtick styling is heavier than necessary for the amount of text.

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?

For an irreversible mutation with no output schema, the description supplies everything material: prerequisite, replacement semantics, error condition, field-level edge cases, and an explicit confirmation instruction. Nothing an agent needs to call it correctly 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 50% and the nested options object is undocumented, but the description compensates for the highest-risk fields: notes semantics, the discharge combination constraint, and the at-least-one-field rule. Values for flow, moods, sexDrive, etc. remain unexplained.

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 ('Logs a day's cycle-tracking entry') plus the content domain (symptoms, moods, flow, notes) and the per-day scope. This cleanly separates it from siblings like update_menstrual_calendar, get_menstrual_data_for_date, and confirm_menstrual_period_start.

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 prerequisite ('needs cycle tracking set up in Garmin Connect first') and an explicit pre-call directive ('IRREVERSIBLE: confirm with the user before calling'). It does not, however, name when to prefer this over update_menstrual_calendar or other menstrual siblings.

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