Set the selection of Blender objects for subsequent operations. Define which objects are active and whether to replace or extend the existing selection.
Set the selection. Tools that default to "the selection" use this.
| Name | Required | Description | Default |
|---|---|---|---|
| names | Yes | Objects to select | |
| active | No | Which of them becomes active | |
| extend | No | Add to the selection instead of replacing it |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
There are no annotations, so the description carries the full burden of behavioral disclosure. It only says 'Set the selection' with no mention of side effects, such as whether the selection is replaced or extended by default, or what happens to the active object. The extend parameter is documented only in the schema, not in the description.
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 description is extremely concise, consisting of two short sentences. The key purpose is stated first, and there is no fluff. It is appropriately sized for a simple setter tool, though it could afford a bit more detail without becoming verbose.
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 selection tool with three parameters fully described in the schema, the description provides the minimal context needed: what the tool does and its role in the broader workflow. It does not explain the default behavior (replace vs. extend) or what 'active' means beyond the schema, which an agent might need to know for correct invocation.
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 all three parameters (names, active, extend) are documented in the schema. The description adds no additional meaning beyond the schema, so it meets the baseline for a tool with high schema coverage.
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 states a clear verb ('Set') and resource ('the selection'), so the core action is identifiable. However, it is vague about what kind of selection (objects) and does not distinguish itself from related tools like get_selected_objects or set_active_object, which are siblings.
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 phrase 'Tools that default to \
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.