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get_usd_prim_info

Read-onlyIdempotent

Read a registered USD stage prim's name, type, active state, parent, child count, schemas, variants, and common-type flags. Missing prims return is_valid=false with a note, not an error.

Instructions

Read one prim of a registered USD stage: name, type_name, active, parent_path, direct children_count, applied_schemas, variant_sets and an is_a map for nine common types (Xform, Mesh, Cube, Scope, Camera, four lights). A missing prim returns is_valid=false with a note, not an error. Read-only.

Returns: { name: string, prim_path: string, type_name: string, active: bool, is_valid: bool, is_pseudo_root: bool, parent_path: string, children_count: number, applied_schemas: [string], variant_sets: [string], is_a: { Xform, Mesh, Cube, Scope, Camera, DistantLight, SphereLight, RectLight, MeshLight: bool } }, or { prim_path, is_valid: false, note } when the prim does not exist

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
prim_pathYesAbsolute SdfPath of the prim to read, e.g. "/World/Cube".
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.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changedv1.2.0
    • changedInput schema / properties / prim_path / description
      Previous value: -"Target prim path"New value: +"Absolute SdfPath of the prim to read, e.g. \"/World/Cube\"."
    • 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

A4.1/5.0
Behavior4/5

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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description adds genuinely useful behavior beyond them by specifying that a missing prim returns is_valid=false with a note rather than an error, and by detailing the is_a map contents.

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?

Front-loaded with the read action and the special case, then a clearly delimited Returns block. The field list is repeated between the opening sentence and the Returns block, a minor redundancy, but otherwise tight and well structured.

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

Completeness4/5

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

There is no output schema, so the description correctly carries the return shape and the missing-prim fallback, which is what an agent needs. It does not explain how to obtain stage_name (left to the schema) but is otherwise complete for a simple read tool.

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 prim_path and stage_name fully. The description adds no extra parameter syntax or format meaning beyond what the schema provides, so the baseline 3 applies.

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

Purpose5/5

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

States a specific verb (Read) and resource (one prim of a registered USD stage), then enumerates the exact fields returned including the is_a type map, which clearly separates it from siblings like list_usd_prims and get_usd_prim_metadata.

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

Usage Guidelines4/5

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

Gives clear context for reading a single prim and clarifies the missing-prim case, but never routes the agent against alternatives (list_usd_prims, get_usd_attribute_value) or states prerequisites for resolving the stage. Clear context without explicit when-not guidance.

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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