Google Play MCP

set_rollout_fraction

Adjust the user percentage of a staged rollout on a Google Play track to control release exposure. Preview changes with a dry run before updating the fraction.

Instructions

Change the percentage of a staged rollout (e.g. 0.05 → 0.2). Finds the staged release on the track (default production); userFraction is strictly between 0 and 1 — use complete_rollout for 100%. Gated on production by PLAY_MCP_ALLOW_PRODUCTION_RELEASE. Set dryRun:true to preview before/after.

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": {
      "packageName": "<packageName>",
      "userFraction": "<userFraction>"
    },
    "name": "set_rollout_fraction"
  }
}

Input Schema

Name	Required	Description
`track`	No	Default 'production'
`dryRun`	No	Preview only: open a temporary edit, apply, validate, then delete it. Nothing is published (default false). Ignored when editId is set.
`editId`	No	Optional: an open edit from insert_edit. The change is applied inside that edit and NOT committed — batch several changes, then call commit_edit.
`packageName`	Yes	Application id (package name), e.g. com.example.app
`versionCode`	No	Target the release containing this code (default: the staged one)
`userFraction`	Yes	New fraction, 0 < fraction < 1 (0.2 = 20%)
`changesNotSentForReview`	No	Commit option: keep the changes out of review until sent from Play Console. Google requires this for some apps and rejects it for others — set it only if a commit error asks for it.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 10, 2026

TDQS

A4.2/5.0

Behavior4/5

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

With no annotations, the description carries disclosure duties and does reasonably well: it reveals the environment-variable production gate (PLAY_MCP_ALLOW_PRODUCTION_RELEASE), the lookup behavior (finds the staged release on the track), and the preview semantics. It omits error behavior when no staged release exists and does not state irreversibility of a fraction change.

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?

Four compact clauses, zero filler, and the core action and example transition are front-loaded before the constraints. Every sentence supplies information an agent needs.

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

Completeness4/5

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

For a 7-parameter mutation tool with no annotations and no output schema, the description covers the action, scoping, safety gate, and preview path. It falls short only on failure modes (missing staged release, invalid fraction handling) which the schema does not cover either.

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 baseline is 3. The description reinforces the 0 < userFraction < 1 bound and default production track with a concrete example, but this largely repeats what the schema already documents rather than adding new meaning.

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+resource (change the percentage of a staged rollout) with a concrete example transition (0.05 → 0.2), and explicitly distinguishes itself from complete_rollout for the 100% case. An agent can identify the operation without reading the schema.

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?

Gives clear when-to-use context: change a staged rollout fraction on a track defaulting to production, use complete_rollout when going to 100%, and set dryRun:true to preview. It does not mention sibling halt_rollout/resume_rollout as alternatives, so routing coverage is good but not exhaustive.

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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