set_units

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

With no annotations, the description carries the full burden and does add genuine behavioral detail: the setting is applied and then read back, and a disagreeing readback yields an error rather than false success. That write-then-verify semantic is valuable. It stops short of stating side effects on existing geometry/dimensions or document-open prerequisites.

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?

Three sentences, front-loaded with the purpose, then accepted values and then the verification behavior. No filler; the alias clause and readback clause each earn their place.

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 structure needn't be explained, and the description covers accepted inputs and the verification contract. For a single-parameter setter this is nearly complete; only document-open prerequisites and side effects on existing model data remain unaddressed.

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 100%, so the baseline is 3, but the description adds value beyond the schema by documenting that common aliases like 'inch' or 'millimeters' are accepted, which the schema's enum-like list ('mm, cm, m, in, or ft') does not mention.

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 precise verb and resource: 'Set the active document's linear unit system.' The scope ('active document') and the target (unit system) are unambiguous, and no sibling tool competes for this purpose.

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 implies when the tool applies (setting the active document's units) but gives no explicit when-to-use guidance, prerequisites, or exclusions. There is no named alternative to steer toward, so usage is only implied rather than stated.

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