Unity MCP Server

bridge_live_fetch

Fetch live Unity Editor state through the opt-in localhost bridge, such as hierarchy, console logs, or screenshots. Requests are refused when the bridge is disabled.

Instructions

Fetch live Editor state via the opt-in localhost bridge (e.g. /hierarchy, /console, /screenshot). Refused when bridge disabled.

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": {
      "path": "<path>"
    },
    "name": "bridge_live_fetch"
  }
}

Input Schema

Name	Required	Description	Default
`path`	Yes	Bridge path, e.g. /hierarchy or /console?limit=50

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.5.2Nov 11, 2026

TDQS

B3.3/5.0

Behavior2/5

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

No annotations are supplied, so the description carries the full behavioral burden. It discloses two meaningful traits — localhost-only transport and refusal when the bridge is disabled — but says nothing about read-only versus mutating behavior, latency/timeouts, whether /screenshot returns binary/base64 payloads, or what error shape a refusal takes.

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?

Two short sentences, scoping and examples front-loaded, with the failure condition last. Nothing is redundant or padded.

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?

With one required param and no output schema, the description should convey what comes back per path — especially for /screenshot, whose return type plausibly differs from /hierarchy. It covers the invocation gate (bridge enabled) but leaves the response side entirely unspecified.

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 single 'path' parameter is already documented with an example including a query string ('/console?limit=50'). The description's examples reinforce the schema but add no new meaning, which is the baseline-3 case.

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?

States a specific verb ('Fetch') and resource ('live Editor state') plus the transport mechanism ('opt-in localhost bridge'), with concrete example paths (/hierarchy, /console, /screenshot). An agent can distinguish this from the status-oriented sibling get_bridge_status, though the description never explicitly contrasts them.

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

Usage Guidelines3/5

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

Usage is implied rather than stated: it is for live Editor state instead of static/cached data, and it only works when the opt-in bridge is enabled. The 'Refused when bridge disabled' clause is a useful precondition, but no alternative tool is named for the disabled case (e.g., checking bridge status first).

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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