pymol-mcp

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Set Background

set_background

Sets the render background color for PyMOL molecular visualizations, allowing you to choose colors such as white or black.

Instructions

Set the render background color.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "set_background"
  }
}

Input Schema

Name	Required	Description	Default
`color`	No	Background color name, e.g. 'white', 'black'.	white

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 15, 2026

TDQS

B3.1/5.0

Behavior2/5

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 states the mutation target ('render background color') but does not say whether the setting persists across renders or session resets, what happens to existing backgrounds, or whether the operation has side effects beyond rendering.

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?

The definition is a single front-loaded sentence with no redundant wording. Every word contributes to identifying the action and its target.

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

Completeness3/5

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

The parameter is fully described in the schema and an output schema exists, so return behavior need not be explained. However, for a mutation tool with no annotations, the description is minimal and omits behavioral details like persistence and scope of effect.

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 the single 'color' parameter with examples and a default. The description adds no format, naming, or validation meaning beyond what the schema supplies.

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?

The description gives a specific verb and resource: 'Set the render background color.' It is clear what the tool does and implicitly differentiates from the sibling 'color' by scoping to the render background, but it does not explicitly name or contrast that alternative.

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

Usage Guidelines2/5

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

There is no guidance on when to use this tool versus alternatives such as 'color' or 'render_image', nor any preconditions or exclusions. Usage is only tautologically implied by the purpose statement.

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