set_selection

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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the safety profile is covered. The description does add genuine context by locating the effect in 'FreeCAD's viewport', implying a UI-level state change rather than a model or file mutation. It does not disclose what happens to a prior selection or whether a document must be active.

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?

A single tight sentence with the most useful information — the accepted name format — front-loaded. Nothing is redundant, though the parenthetical example is doing work that a short clause on selection-replacement behavior could have shared.

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 values need no explanation. However, for a 3-parameter state-changing tool with zero schema description coverage, the description leaves the document scoping and clear-first replacement semantics undocumented, which is not enough to call it correctly on the first try.

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 carries the full burden and only partially meets it: 'names' is clarified by the sub-element example format, but 'doc_name' and especially 'clear_first' (which defaults to true and therefore replaces the existing selection) are entirely unexplained. The distinction between adding to and replacing the current selection is exactly what an agent would get wrong here.

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 pair ('Highlight/select') and resource ('objects or sub-elements') scoped to FreeCAD's viewport, which is far more informative than the bare name. The concrete example ['Pad', 'Pad.Face1'] shows the accepted naming form, letting an agent distinguish this from document-level mutators. It does not explicitly contrast with the sibling get_selection, so it stops short of a 5.

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?

There is no statement of when to use this versus get_selection, nor any precondition (e.g. an open document or GUI session must exist). The agent must infer from the name alone that this writes selection state while get_selection reads it.

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