pix-mcp

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pix_perform_playback

Idempotent

Replay a captured GPU workload to reproduce behavior and analyze timing, with options for looping, CPU timing, cycle measurement, and timeout control.

Instructions

Replay the capture once (or in a loop), optionally timing command-list recording.

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": {
      "capture_id": "<capture_id>"
    },
    "name": "pix_perform_playback"
  }
}

Input Schema

Name	Required	Description	Default
`loop`	No
`time_cpu`	No
`capture_id`	Yes
`loop_count`	No
`measure_cycles`	No
`timeout_seconds`	No
`working_directory`	No
`do_not_expand_executeindirect`	No

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 9, 2026

TDQS

C2.9/5.0

Behavior3/5

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

Annotations already provide idempotent and non-destructive hints, so the description does not need to repeat those. It adds some behavioral context by mentioning looping and optional timing of command-list recording, but it does not disclose side effects, prerequisites, or what happens during replay.

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?

The description is a single, front-loaded sentence with no wasted words. However, it is so brief that it sacrifices necessary detail for an 8-parameter tool.

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?

Given the large parameter set and the existence of similar playback-related siblings, the description is incomplete. It does not explain the required capture_id, the meaning of timing command-list recording, or how this relates to pix_recapture_playback, making correct invocation reliant on guesswork.

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% and there are 8 parameters, so the description must compensate but does not. It vaguely hints at loop behavior and timing options, but it never names parameters like capture_id, loop_count, timeout_seconds, or working_directory, leaving their semantics unexplained.

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 states a specific action ('Replay the capture') and mentions optional loop and timing behavior, making the core purpose clear. It does not distinguish this tool from the similarly named sibling pix_recapture_playback, so it lacks explicit differentiation.

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 about when to use this tool versus alternatives, no prerequisites, and no exclusions. The description only says what the tool does, leaving the agent to infer usage conditions such as requiring an already-open capture.

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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