nav_add_modifier_volume

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

No annotations are provided, so the description must carry the full behavioral burden. It clearly states that an actor is spawned, but it does not disclose side effects such as whether existing volumes are replaced, whether the navmesh is modified despite the 'rebuild' parameter, or what happens when default values are used. For a creation tool, this is a meaningful gap.

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 compact and front-loaded with the main purpose, followed by the most important parameter guidance, a KB reference, and an example. Each section earns its place with no redundant wording. The example is useful, though showing a populated call might have been slightly more informative.

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 tool with five optional parameters and no schema descriptions, the description covers the most domain-specific behavior (area_class) and points to a KB resource, but it omits coordinate/unit details for extent and location, the meaning of rebuild, and any required scene conditions. Since an output schema exists, return values need not be explained, but the parameter gaps keep this from being fully complete.

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 must compensate. It does provide valuable semantics for 'area_class' by explaining the three categories of valid values. However, the other four parameters (extent, location, rebuild, actor_name) receive no explanation beyond their names, which are only partially self-descriptive. The example of a no-argument call does add some context, but coverage is incomplete.

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 opens with a specific verb-resource pair: 'Spawn a NavModifierVolume with the requested nav area class.' It defines the tool's unique role among nav tools by focusing on modifier volumes and area classes, and the three use cases for area classes further clarify what the tool accomplishes. The distinction from siblings like setup_navmesh or place_navmesh_bounds_volume is implicit but clear from the domain.

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 gives concrete guidance on which area class to use ('NavArea_Null' to block, 'NavArea_Obstacle' for high cost), which helps the agent choose parameter values. However, it does not state when to prefer this tool over the other nav tools in the sibling list, nor does it mention any exclusions or prerequisites. Usage is implied rather than explicitly contrasted with alternatives.

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