PureData-MCP

Open Existing Pure Data Patch

pd_open_patch

Launch a .pd patch from its absolute path to enable MCP-driven status, preview, save, and stop operations.

Instructions

Launch an existing absolute .pd patch path as the MCP-managed Pd process for status, preview, save, and stop.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "patchPath": "<patchPath>"
    },
    "name": "pd_open_patch"
  }
}

Input Schema

Name	Required	Description	Default
`gui`	No
`patchPath`	Yes
`audioOutDevice`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.3.2Aug 8, 2026

TDQS

A3.7/5.0

Behavior3/5

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

With no annotations, the description carries the full burden. It discloses that the patch becomes the MCP-managed process and lists supported operations, which adds context beyond the schema. But it omits side effects such as whether an existing process is replaced, blocking behavior, or error handling, so transparency is only partial.

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 description is a single sentence with no filler, front-loaded with the verb and key resource. It is concise and every word earns its place.

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

Completeness2/5

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

The tool has 3 parameters, no output schema, and no annotations. The description explains the main purpose but not return values, errors, process lifecycle, or how it interacts with already-running sessions. This leaves significant operational gaps, especially given the richness of the sibling tool set.

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

Parameters2/5

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

Schema description coverage is 0%, so the description must compensate. It adds meaning to patchPath by specifying 'absolute .pd' path, but it does not explain gui or audioOutDevice. Since two of three parameters remain undocumented, the description only partially compensates for the lack of schema descriptions.

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 uses a specific verb 'Launch' and names the resource 'existing absolute .pd patch path', clarifying it becomes the MCP-managed process for status, preview, save, and stop. This clearly distinguishes it from siblings like pd_create_live_patch or pd_start_live_session that create or start without opening an existing file.

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?

The description implies when to use this tool: to open an existing patch as the central MCP-managed process before performing status, preview, save, or stop operations. However, it does not explicitly state when not to use it or name alternative tools, so it stops short of full usage guidance.

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