When to use: Perform a lightweight clash analysis between two Revit categories (e.g. Mechanical Equipment vs Structural Framing) using bounding-box overlap where available, falling back to shared-Level proximity, then annotate with any matching VDC rules stored in the D1 database. When NOT to use...
Part of the Revit MCP server.
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AI agents call revit_clash_detect to retrieve information from Revit MCP without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though revit_clash_detect only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"revit_clash_detect": {}
}
}See the full Revit MCP policy for all 8 tools.
These attack patterns abuse exactly the kind of access revit_clash_detect gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
When to use: Perform a lightweight clash analysis between two Revit categories (e.g. Mechanical Equipment vs Structural Framing) using bounding-box overlap where available, falling back to shared-Level proximity, then annotate with any matching VDC rules stored in the D1 database. When NOT to use: Do not use as a substitute for Navisworks Manage for contractual clash reports — this is a first-pass coordination sniff test, not a certified Clash Detective run. APS scopes: data:read viewables:read (Model Derivative metadata + properties). Rate limits: APS default ~50 req/min per app per endpoint; Model Derivative translation jobs ~60 req/min; OSS uploads size-limited per file to 100MB for direct upload, larger via resumable. Errors: 401 APS token expired — refresh. 403 scope insufficient — add viewables:read. 404 URN not found — verify model_id. 429 rate limited — back off. 5xx APS upstream — retry with jitter. Side effects: Read-only against APS. May read from D1 vdc_rules table if present. Idempotent.. It is categorised as a Read tool in the Revit MCP MCP Server, which means it retrieves data without modifying state.
Register the Revit MCP server in PolicyLayer and add a rule for revit_clash_detect: 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 Revit MCP. Nothing to install.
revit_clash_detect is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the revit_clash_detect 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 revit_clash_detect. 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.
revit_clash_detect is provided by the Revit MCP server (https://revit-mcp.itmartin24.workers.dev/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 8 Revit MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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