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

Annotations already flag readOnlyHint=false, idempotentHint=true and destructiveHint=true; the description explains the mechanism behind that destructiveness ('an explicitly null field is CLEARED; omitted fields are untouched'). It also discloses side effects (goal_candidates from the profile) and the key intake/next_field return, adding real context beyond the annotations.

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?

The core purpose is front-loaded, but the description is dense and runs long, particularly the intake {complete, next_field, ...} and goal_candidates clauses that return-value details an output schema could carry. It is informative but not tightly edited.

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 complex tool with a nested patch object, many optional fields and a large surface, the description covers the write/clear semantics, injury routing, and notable return behaviors. With an output schema present it need not detail every return field, so remaining gaps are minor.

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 100%, so the baseline is 3; the description earns above it by clarifying null-clears-versus-omitted-untouched semantics, which the schema only partially states ('omitted fields are unchanged'). It adds genuine meaning to how the patch object should be constructed.

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 (persist) and resource (user-confirmed coach profile facts) and enumerates the fact categories it covers (goal, experience, schedule, equipment, injuries, preferences). It names sibling-adjacent concepts (upsert_goal's shape, add_injuries/resolve_injury_areas) but does not explicitly contrast itself with sibling write tools like update_session or upsert_goal.

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 context that only user-confirmed facts should be persisted and that it works mid-workout, and routes injury handling to add_injuries/resolve_injury_areas. However it never states when to prefer this tool over siblings such as upsert_goal, and offers no explicit exclusions.

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