v0.1 capability-token sink challenge (M1). Sink issues a signed canonical action statement. Returns the SinkChallenge and its challenge_hash. Used to bind the gateway's later policy evaluation to a specific action the sink authored. Search keywords: capability token, sink challenge, M1.
Risk signalsHigh parameter count (13 properties)
Part of the Agent Passport System — Cryptographic Identity for AI Agents server.
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AI agents use aps_capability_issue_challenge to create or modify resources in Agent Passport System — Cryptographic Identity for AI Agents. 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 aps_capability_issue_challenge 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 Agent Passport System — Cryptographic Identity for AI Agents.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"aps_capability_issue_challenge": {
"limits": [
{
"counter": "aps_capability_issue_challenge_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Agent Passport System — Cryptographic Identity for AI Agents policy for all 150 tools.
These attack patterns abuse exactly the kind of access aps_capability_issue_challenge 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.
v0.1 capability-token sink challenge (M1). Sink issues a signed canonical action statement. Returns the SinkChallenge and its challenge_hash. Used to bind the gateway's later policy evaluation to a specific action the sink authored. Search keywords: capability token, sink challenge, M1.. It is categorised as a Write tool in the Agent Passport System — Cryptographic Identity for AI Agents MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Agent Passport System — Cryptographic Identity for AI Agents MCP server in PolicyLayer and add a rule for aps_capability_issue_challenge: 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 Agent Passport System — Cryptographic Identity for AI Agents. Nothing to install.
aps_capability_issue_challenge 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 aps_capability_issue_challenge 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 aps_capability_issue_challenge. 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.
aps_capability_issue_challenge is provided by the Agent Passport System — Cryptographic Identity for AI Agents MCP server (agent-passport-system-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 150 Agent Passport System — Cryptographic Identity for AI Agents tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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