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photoshop_create_clipping_mask

Idempotent

Creates a clipping mask on a layer so it shows only where the layer below has opaque pixels. Use to clip a layer to the shape beneath it.

Instructions

Create a clipping mask on the active layer (or a named layer).

Users often say: clip to layer below, clipping mask, clip this layer, mask to shape below.

Use when: the active layer should be visible only where the layer directly below it has opaque pixels. Do NOT use when: the layer is already clipped — returns success with already_clipping. Do NOT use when: the layer is the bottom-most layer — there is no base layer to clip into.

Returns: JSON { ok, summary, details: { layer_name, is_clipping, already_clipping? } }. Preconditions: active document; target layer must sit directly above the base layer below it in the same group/stack. Side effects: one history step (groupEvent).

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
layer_nameNoOptional exact layer name (recursive search). Default: active layer.
document_idYesPhotoshop document id from photoshop_get_state / photoshop_list_documents. Send null or 0 to use the active document. A positive number activates that document before the tool runs. When no document is open, a stale id does not block the call.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changedv1.7.33
    • changedInput schema / properties / document_id / description
      Previous value: -"Photoshop document id from photoshop_get_state / photoshop_list_documents. Send null to use the active document. A number activates that document before the tool runs."New value: +"Photoshop document id from photoshop_get_state / photoshop_list_documents. Send null or 0 to use the active document. A positive number activates that document before the tool runs. When no document is open, a stale id does not block the call."
  2. Changed4 schema fields changedv1.7.32
    • addedInput schema / additionalProperties
      Added value: +false
    • changedInput schema / properties / document_id / description
      Previous value: -"Optional Photoshop document id from photoshop_get_state / photoshop_list_documents. When set, the tool activates that document before running so a UI tab switch cannot retarget the edit."New value: +"Photoshop document id from photoshop_get_state / photoshop_list_documents. Send null to use the active document. A number activates that document before the tool runs."
    • changedInput schema / properties / document_id / type
      Previous value: -"number"New value: +[
      +  "number",
      +  "null"
      +]
    • addedInput schema / required
      Added value: +[
      +  "document_id"
      +]
  3. First observedv0.1.0

TDQS

A4.7/5.0
Behavior5/5

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

Annotations already declare non-destructive/idempotent, but the description goes further: it names the already_clipping success case, spells out preconditions (active document, target must sit directly above its base in the same group), and discloses the side effect (one history groupEvent step). This is rich context beyond structured fields.

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?

Front-loaded with the action, then synonym phrases for user intent, then when/when-not, then returns, preconditions, and side effects in labeled blocks. Every sentence carries distinct information with no waste.

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?

With no output schema, the description supplies the return JSON shape (ok, summary, details with layer_name, is_clipping, already_clipping). Combined with preconditions, side effects, and exclusions, an agent has everything needed to call it correctly.

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 both parameters are fully documented in the schema. The description repeats that layer_name defaults to the active layer but adds no syntax or format detail beyond what the schema provides, so 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 (Create) and resource (clipping mask) with scope (on the active layer or a named layer). It is immediately distinguishable from the sibling photoshop_release_clipping_mask.

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?

Explicit 'Use when' condition (layer should be visible only where the layer below has opaque pixels) and two explicit 'Do NOT use when' exclusions (already clipped; bottom-most layer) with the resulting behavior noted. Nothing is left to inference.

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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