measurements_update_weight

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

With no annotations, the description carries the behavioral burden. It discloses a key trait: partial update semantics ('Only provided fields are changed'), which prevents an agent from assuming unspecified fields are cleared. It could add error/validation behavior, but the core update behavior is explicit.

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 sentences with no filler. The purpose is front-loaded and the partial-update nuance is stated in the second sentence without redundancy.

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 simple 4-parameter update with 100% schema coverage and an output schema, the description is complete: it identifies the target resource, the action, and the crucial partial-update behavior. No critical contextual information 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 description coverage is 100%, so the schema already documents weight_id, date, notes, and weight. The description adds no parameter-specific detail beyond restating partial-update behavior, so the 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?

The description uses a specific verb and resource ('Update an existing weight record') that clearly identifies this as the update tool for weight measurements. It distinguishes itself from sibling create/delete weight tools and from update tools for other measurement types.

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 description makes the context clear: use this when an existing weight record needs to be changed. It does not explicitly list exclusions or alternatives, but the sibling set and the phrase 'existing' imply it is not for creation or deletion.

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