P109 — pull a Hacker News post's score + comments + top replies via the public HN API and write them to the action's metadata.proof. USE WHEN a published Hacker News action is ripe for 24h measurement (checks the publishedUrl on the action, parses the item id, calls the Firebase API). Auto-create...
Part of the ChiefLab server.
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AI agents use chieflab_measure_hacker_news to create or modify resources in ChiefLab. 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 chieflab_measure_hacker_news 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 ChiefLab.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"chieflab_measure_hacker_news": {
"limits": [
{
"counter": "chieflab_measure_hacker_news_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full ChiefLab policy for all 45 tools.
These attack patterns abuse exactly the kind of access chieflab_measure_hacker_news 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.
P109 — pull a Hacker News post's score + comments + top replies via the public HN API and write them to the action's metadata.proof. USE WHEN a published Hacker News action is ripe for 24h measurement (checks the publishedUrl on the action, parses the item id, calls the Firebase API). Auto-creates a next-move action based on the outcome (trending → reply + cross-post; engaged → reply; stalled → rewrite angle). Idempotent — second call returns the existing measurement. No API key required; HN is public-read.. It is categorised as a Write tool in the ChiefLab MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the ChiefLab MCP server in PolicyLayer and add a rule for chieflab_measure_hacker_news: 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 ChiefLab. Nothing to install.
chieflab_measure_hacker_news 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 chieflab_measure_hacker_news 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 chieflab_measure_hacker_news. 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.
chieflab_measure_hacker_news is provided by the ChiefLab MCP server (@chieflab/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 45 ChiefLab tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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