AI agents invoke build_spm_package to trigger actions in Xcode. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
Building a Swift package can execute arbitrary code through build scripts, package dependencies, and build phases. This has external side effects (compilation, resource generation, artifact creation) whose outcomes depend on package contents and configuration.
From the tool's definition Tool name 'build_spm_package' and description 'Builds a Swift Package Manager package directly using' indicate execution of a build process.
Documented attack patterns abuse exactly the kind of access build_spm_package gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Xcode, and nothing reaches the server without passing your rules. This is the rule we recommend for build_spm_package:
{
"version": "1",
"default": "deny",
"tools": {
"build_spm_package": {
"limits": [
{
"counter": "build_spm_package_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}build_spm_package stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Builds a Swift Package Manager package directly using. It is categorised as a Execute tool in the Xcode MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Xcode MCP server in PolicyLayer and add a rule for build_spm_package: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Xcode. Nothing to install.
build_spm_package is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the build_spm_package rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for build_spm_package. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
build_spm_package is provided by the Xcode MCP server (xcode-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 69 Xcode tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
69 Xcode tools catalogued and risk-classified — across an index of 42,500+ MCP servers.