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edit_hda_interface

Modify HDA parameter interface by inserting, removing, hiding, replacing, or moving parameters atomically, ensuring no component-name collisions.

Instructions

Edit an HDA's EXISTING Type Properties interface in one atomic call: insert at a position, remove, hide/show, replace, modify, move.

set_hda_interface only appends. Every op here works on the definition's parameter group; all ops are applied to a copy, the result is checked for component-name collisions, and it is written once — a failing op changes nothing. Read the interface first with get_parm_template_tree.

Ops (dicts, applied in order): {"op": "insert", "spec": {...}, "after": name | "before": name | "in_folder": label or [labels]} — omit the position to append. spec is a set_hda_interface spec, plus types button (with "callback", Python by default), separator, label, vector, color, file, oppath; and fields naming_scheme (base1|xyzw|rgba|minmax| startend|uvw), default_expression, hidden, join_with_next, callback, tags; folder_type "multiparm" for a multiparm block (children named "item#"). {"op": "remove", "name": name_or_folder_label} {"op": "hide" | "show", "name": ...} {"op": "replace", "name": ..., "spec": {...}} {"op": "modify", "name": ..., <label | help | default | default_expression | min | max | min_strict | max_strict | hide_when | disable_when ("" clears) | hidden | join_with_next | menu_items | callback | naming_scheme | new_name | tags>} ("rename", "set_conditional", "set_default" are aliases) {"op": "move", "name": ..., "after" | "before" | "in_folder": ...}

Names are template names (t, not tx; stud_count); folders are addressed by label ("Controls"). Built-in parameters of the node type (an Object's Transform) cannot be removed — Houdini re-adds them at the top level and the reply says so in reinstated_by_houdini; hide them.

Args: ctx: MCP context. node_path: An instance of the HDA whose definition is edited. ops: Operations, in order. dry_run: Validate and report the plan without writing.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
opsYes
dry_runNo
node_pathYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. Addedv2.18.0

TDQS

A5/5.0
Behavior5/5

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

With no annotations, the description carries full behavioral burden, and it excels: it discloses the atomic write-once semantics, copy-and-collision-check, the reinstatement behavior for built-in parameters (including the `reinstated_by_houdini` reply), and the dry_run mode. This far exceeds what a typical descriptionsafe.

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

Conciseness5/5

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

Although long, the description is structured with a clear positional summary, a list of ops, and an Args block. Every segment earns its place: the atomic behavior, the alternatives comparison, the op syntax, edge cases like built-in parameters. It is front-loaded with purpose and semantics, then dives into necessary detail.

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?

There is no output schema, but the description explains the only output detail needed: the possibility of `reinstated_by_houdini` in the reply. It covers prerequisites, atomicity, naming conventions, folder addressing, and all known edge cases. Nothing essential is missing for an agent to invoke it correctly.

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

Parameters5/5

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

Schema coverage is 0%, but the description compensates completely. It explains node_path as 'an instance of the HDA whose definition is edited', ops as 'Operations, in order', and dry_run as 'Validate and report the plan without writing.' It then documents every operation structure in detail (insert, remove, hide/show, replace, modify, move) with nested fields and aliases.

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?

The description opens with a clear verb-resource statement: 'Edit an HDA's EXISTING Type Properties interface' and enumerates the exact operations: insert, remove, hide/show, replace, modify, move. It explicitly contrasts itself with set_hda_interface ('only appends'), making sibling distinction immediate.

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

Usage Guidelines5/5

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

It gives direct guidance: 'set_hda_interface only appends' implies this tool is for modifying existing interfaces. It also instructs the agent to 'Read the interface first with get_parm_template_tree', a concrete prerequisite. The description also clarifies atomic behavior, which directly informs when this is the right call.

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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