Exa and Dome

1. 01

   Add the Exa MCP server

   Exa reads its API key from the x-api-key header. Dome stores the key and sends it on every call.

   $ dome tools add --name exa \
     --url https://mcp.exa.ai/mcp \
     --auth-method api-key \
     --credential-type shared \
     --authorization "Bearer $EXA_API_KEY" \
     --secret-value EXA_API_KEY=$EXA_API_KEY \
     --header-secret x-api-key=EXA_API_KEY \
     --gateway prod-gateway

2. 02

   Sync the catalog

   Sync lists web_search_exa, web_fetch_exa and agent_run. Agents see none of them until it runs.

   $ dome tools catalog sync exa

3. 03

   Block personal data in arguments

   A JSON filter on the request direction scans every argument. A match blocks the call before it reaches Exa.

   $ cat > query-leak.json <<'EOF'
   $ {"json":{"components":[{"fieldActions":[{
     "matcher":{"contentMatchers":[{"ssn":{}},{"creditCard":{"requireLuhn":true}},{"email":{}}]},
     "action":"FILTER_ACTION_BLOCK"}]}]}}
   $ EOF
   $ dome guards filters create query-leak --config-from query-leak.json
   $ dome tools guards filters set exa --direction request --filters query-leak

4. 04

   Apply the rules

   The rule is scoped to deal-scout. Simulate a query with each spelling of the codename, then deploy.

   $ dome rules apply exa-queries.cedar --agent deal-scout --name exa-queries

5. 05

   Cap the calls

   The quota counts every tool call the agent makes. Past the limit, calls are refused until the window resets.

   $ dome quotas set --subject agent --agent deal-scout \
     --dimension tool --unit calls --limit 500 --window daily

Commands and rules tested against a Dome workspace on October 1, 2026. For anything about Exa itself, see Exa's documentation.

permit (principal, action == Dome::Action::"mcp:call", resource is Dome::MCPTool)
when {
  resource.connection_name == "exa" &&
  ["web_search_exa", "web_fetch_exa"].contains(resource.tool_name)
};
 
forbid (principal, action == Dome::Action::"mcp:call", resource is Dome::MCPTool)
when {
  resource.connection_name == "exa" &&
  !["web_search_exa", "web_fetch_exa"].contains(resource.tool_name)
};
 
forbid (principal, action == Dome::Action::"mcp:call", resource is Dome::MCPTool)
when {
  resource.connection_name == "exa" &&
  resource has arguments &&
  ((resource.arguments has query && resource.arguments.query like "*Halcyon*") ||
   (resource.arguments has objective && resource.arguments.objective like "*Halcyon*"))
};