Add a node to a scene

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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds real behavioral value beyond that: it discloses that the scene file is saved (persistence mutation) and that property strings beginning with res:// are resolved as resources, neither of which is in the structured fields. It omits failure behavior (missing scene, name collision), keeping it out of 5 territory.

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, with the example packed inline rather than expanded into a block. Every clause earns its place by clarifying either persistence or value syntax.

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 6-parameter mutation tool with no output schema, it covers the action, the save behavior, and the non-obvious value semantics; parent path and project defaults are handled by the schema. It leaves undefined what happens when the scene path is invalid or the node name already exists, a modest gap.

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 baseline would be 3, but the description adds syntax beyond the schema: the propertyName→value shape with an inline nested example, plus the res:// resource-loading rule for string values. That is genuine semantic enrichment the schema's terse "Property values to set on the new node" does not provide.

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 ("Add a node to an existing scene") and adds the persistence side effect ("and save it"), which an agent needs. It does not explicitly distinguish itself from siblings like create_scene or load_sprite, so it stops short of 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?

The phrase "existing scene" implies a precondition (the scene must already exist), which is useful usage context, but there is no explicit when-to-use/when-not guidance or named alternative such as create_scene for new scenes. Usage is 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.