Point: Snap (deterministic OSNAP)

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

Annotations already declare readOnlyHint=true, so agents know this operation is safe. The description adds the useful context that the snap is deterministic and prevents drawing errors, but it does not disclose return format, failure modes, or how ref_x/ref_y affect behavior.

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 with no filler. The core action is front-loaded, and the practical guidance about avoiding coordinate guessing is immediately actionable.

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 complete parameter documentation, an output schema, and readOnly annotation, the description plus structured data fully equips an agent to call this tool correctly. No meaningful context 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 fully explains all four parameters. The description adds no parameter-level detail beyond 'entity' and 'snap point', which is acceptable because the schema carries the burden.

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 clearly states a specific action: compute a deterministic snap point on an entity. It is distinct from coordinate-guessing and from generic entity creation, but it does not explicitly differentiate itself from sibling tools like point_intersection or point_tangent.

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 explicitly tells agents to use this tool instead of guessing coordinates, which is the primary use case. However, it does not mention when not to use it or when point_intersection/point_tangent would be the better choice.

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