Feed an observation into a thesis — news, price move, or external event. Consumed in next evaluation cycle to update confidence and edges.
Risk signalsHandles credentials or secrets (apiKey) · Accepts raw HTML/template content (content)
Part of the Simplefunctions server.
Free to start. No card required.
AI agents use inject_signal to create or modify resources in Simplefunctions. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call inject_signal repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Simplefunctions.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"inject_signal": {
"limits": [
{
"counter": "inject_signal_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Simplefunctions policy for all 108 tools.
These attack patterns abuse exactly the kind of access inject_signal gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Feed an observation into a thesis — news, price move, or external event. Consumed in next evaluation cycle to update confidence and edges.. It is categorised as a Write tool in the Simplefunctions MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Simplefunctions MCP server in PolicyLayer and add a rule for inject_signal: 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 Simplefunctions. Nothing to install.
inject_signal is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the inject_signal 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 inject_signal. 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.
inject_signal is provided by the Simplefunctions MCP server (@spfunctions/cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 108 Simplefunctions tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.