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

Annotations only declare readOnlyHint=false, so the description carries most of the load and does add real items: the write is an upsert ('or replace'), meaning an existing entry for that day is overwritten, and the operation is confirm-gated with a preview by default. It stops short of describing what the preview returns or any permission requirements.

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?

Two short clauses with zero filler; the core action leads and the confirm-gating caveat follows. Nothing is redundant with the name or restated.

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 only a single annotation, the description covers the write semantics and confirmation gate but leaves open what the preview response contains and whether replacement loses prior history. Adequate, with clear gaps.

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 75% — confirm and dateISO and clientId are documented, weightKg relies on its name and constraint. The description reinforces the unit ('in kg') and the day granularity that maps to dateISO, but adds little beyond the schema. Baseline 3 is appropriate.

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 (record/replace), resource (a no-app client's weight in kg), and temporal scope (for a day). The write counterpart to get_managed_client_weights is distinguishable, though the sibling read tool is not named explicitly.

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?

The parenthetical '(confirm-gated: previews until confirm: true)' tells the agent how execution works, and 'no-app client' implicitly scopes which clients apply. However, it never says when to use this versus alternatives such as log_client_habit or get_managed_client_weights, nor does it state prerequisites (e.g., coach must manage the client).

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