design_set_vanishing_point

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

No annotations are provided, so the description carries the full burden. It discloses the coordinate normalization model (0-1 = canvas bounds, out-of-range permitted), which is genuinely useful, but says nothing about mutation consequences, error behavior when the target layer isn't a perspective layer, or reversibility.

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 sentences, front-loaded with the action and resource, second sentence delivering the non-obvious coordinate contract. No filler.

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?

With 4 params, full schema coverage, and no output schema, the description covers purpose, scope, and the coordinate system adequately. The remaining gap is what happens on a non-perspective or multi-VP layer, which is partly handled by the schema's 'which' description.

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 baseline is 3; the description goes beyond the schema's terse 'Normalized X/Y coordinate' by defining what normalized means (0-1 spans canvas) and that out-of-range values are legal. It does not elaborate on the 'which' enum or the default-resolution rule, which the schema already covers.

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+resource: 'Update a vanishing point on an existing perspective layer.' The 'existing perspective layer' scoping distinguishes it from creation siblings like design_add_perspective_grid or design_add_perspective_floor, though it doesn't name any sibling 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?

Implies a prerequisite (the layer must already exist and be a perspective layer) but gives no explicit when-to-use guidance, no mention of when to use design_add_perspective_grid/design_add_perspective_floor instead, and no note about which perspective types accept which VP.

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