verify_seal
Verify a seal A or seal B locally, in this process — signature, live agentId, subject and request bindings, expiry, and TEE attestation. Never asks a server whether a seal is valid. An invalid seal is a normal answer: { valid: false, failure } naming the check that failed.
This record as markdown: /tools/0x402-mcp/verify-seal.md
What verify_seal does on 0x402
AI agents call verify_seal to retrieve information from 0x402 without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
now | integer | — | Unix seconds to judge expiry against. Defaults to the current time; set it to audit a seal that has since expired. |
seal | object | Yes | The seal, as a JSON string or an object. |
expectedSubject | string | — | The token this seal is supposed to be about. Omit and the subject/request bindings are only checked for self-consistency. |
Parameters from the server's own tool schema.
Why verify_seal is rated Low
Even though verify_seal only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Attacks that exploit this kind of access
The rule that runs verify_seal safely
PolicyLayer is an MCP gateway: it sits between your AI agents and 0x402, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For verify_seal, this is the rule to start with:
verify_seal is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect 0x402, apply this rule, and every verify_seal call is checked against it from then on.
Questions about verify_seal
Verify a seal A or seal B locally, in this process — signature, live agentId, subject and request bindings, expiry, and TEE attestation. Never asks a server whether a seal is valid. An invalid seal is a normal answer: { valid: false, failure } naming the check that failed. It is categorised as a Read tool in the 0x402 MCP Server, which means it retrieves data without modifying state.
verify_seal accepts 3 parameters: now, seal, expectedSubject. Required: seal. The full parameter table on this page comes from the server's own tool schema.
Register the 0x402 MCP server in PolicyLayer and add a rule for verify_seal: 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 0x402. Nothing to install.
verify_seal 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 verify_seal 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 verify_seal. 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.
verify_seal is provided by the 0x402 MCP server (@0x402/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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