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

Annotations already declare destructiveHint=true and readOnlyHint=false, so safety is covered and the bar is lower. The description adds genuine behavioral context by stating that an empty string clears the note (which explains the destructive hint) and that content is capped at 500 chars. It does not mention permissions or reversibility beyond clearing, so it is useful but not rich.

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 the verb and resource, then layers scope, content examples, and the clearing behavior. It is dense and mostly earned, though the examples ('key session, commit') and the 500-char restatement add some length that could be trimmed.

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 a mutation tool with no output schema and annotations covering the safety profile, the description adequately covers what the note is, its length limit, when to use it versus a day note, and how to clear it. The only meaningful gap is the unexplained 'date' parameter.

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 0%, so the description must carry parameter meaning. It explains the iid (from get_plan / plan_workouts) and characterizes the note's content and length well. However, the 'date' parameter (pattern only in schema) is never explained, so the description does not fully compensate for the coverage gap.

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 (Write) and precise resource (the note on one scheduled workout), and explicitly distinguishes its scope from a day note ('what belongs to this session goes HERE, not into a day note'). It even tells the agent where the iid comes from (get_plan / plan_workouts), so it is separable from siblings like set_day_note 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 routing: use this for session-specific content, not a day note, and points to the iid source. It also covers the clearing case ('Empty string clears it'). It does not, however, address the other note-setting siblings (set_activity_notes, set_event_notes, set_strength_notes), so the alternative-selection guidance is partial rather than exhaustive.

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