log_session_note

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

Annotations already declare readOnlyHint=false, destructiveHint=false, openWorldHint=false, so the write profile is known. The description adds genuinely useful non-schema context — storage is local-only and never sent to the wearable provider — but says nothing about whether writes are idempotent, what happens on duplicate day entries, or validation failures.

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?

Four tight sentences, front-loaded with the purpose and the phone-only storage caveat before the extraction instruction. Dense but every clause carries information; no filler.

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?

An output schema exists, so return values need no explanation, and the write-safety story is covered by annotations plus the local-only note. The remaining gap is the unexplained activity_id parameter and the unstated format for day.

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?

Top-level schema coverage is effectively 0%: 'text' and 'activity_id' have no descriptions and 'day' has no format stated. The description rescues 'day' (defaults to today) and clarifies the text/stations split, but 'activity_id' — how to link a note to an existing session — is completely undocumented in both schema and description.

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?

Uses a specific verb (Save) with a clearly scoped resource (a session note for what the wearable cannot see), and explicitly distinguishes this from the wearable-sourced data that siblings like get_training_summary and list_sessions return.

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 concrete invocation guidance: extract structured stations from the athlete's words, keep verbatim text in 'text', and default to today when no day is given. No explicit when-not conditions or named alternatives, but the 'wearable cannot see' framing implicitly tells the agent which sessions this applies to.

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