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list_usd_prims

Read-onlyIdempotent

List child or recursive descendant prims under a prim on a registered USD stage, returning prim_path, type_name, active state, and count.

Instructions

List the prims under one prim (default the pseudo root "/") on a registered USD stage, each with prim_path, type_name and active, plus count: its direct children, or with recursive=true its whole subtree in depth-first order. Only active, loaded, defined, non-abstract prims appear, and instance proxies are not traversed. Read-only.

Returns: { prims: [{ prim_path, type_name, active }], count: number }

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
recursiveNofalse (default) lists the direct children only; true lists every descendant, each parent before its children.
stage_nameNoName the stage was registered under by create_usd_stage or open_usd_stage; a stage already in the USD cache also matches by the end of its root layer identifier.
prim_path_prefixNoSdfPath of the prim whose children are listed; it must exist. Default "/" (the pseudo root).

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed3 schema fields changedv1.2.0
    • changedInput schema / properties / prim_path_prefix / description
      Previous value: -"Path whose children to enumerate. Default: \"/\" (pseudo root)"New value: +"SdfPath of the prim whose children are listed; it must exist. Default \"/\" (the pseudo root)."
    • changedInput schema / properties / recursive / description
      Previous value: -"If true (default), use GetFilteredChildren (traverse instance proxies). If false, GetChildren (direct only)."New value: +"false (default) lists the direct children only; true lists every descendant, each parent before its children."
    • changedInput schema / properties / stage_name / description
      Previous value: -"Stage cache key"New value: +"Name the stage was registered under by create_usd_stage or open_usd_stage; a stage already in the USD cache also matches by the end of its root layer identifier."
  2. First observedv1.1.0

TDQS

A3.8/5.0
Behavior4/5

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

Annotations already declare readOnly, idempotent, non-destructive, non-open-world behavior, so the safety profile is covered. The description adds real filtering semantics beyond that: only active, loaded, defined, non-abstract prims appear, and instance proxies are not traversed.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tight sentences plus an explicit Returns line, with scoping and the recursive condition front-loaded. Dense with no filler, though the Returns block is somewhat run-on.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only listing tool with no output schema, the description supplies the return shape ({prims, count}) and the filtering/traversal rules an agent needs. Nothing essential to correct invocation is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents stage_name, prim_path_prefix, and the recursive flag. The description restates recursive semantics and adds depth-first ordering and the default root, but this is largely redundant with the schema's own descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (list) and resource (prims under one prim on a registered USD stage) and enumerates the returned fields, so the operation is unambiguous. It stops short of naming sibling alternatives like get_usd_prim_info, so differentiation is implicit rather than stated.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies when the tool applies (traversing a prim's children or subtree, defaulting to the pseudo root) but never names a when-not condition or an alternative tool. Usage is inferable from the behavior described rather than explicit.

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

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