decode_jwt
utilpeek: Decode a JWT without verifying it. To check the signature use verify_jwt. Returns a compact JWT split into its header and payload JSON, with alg, typ, kid, whether a signature is present, and the standard claims: iat, nbf and exp as ISO 8601 UTC, plus expired and not_yet_valid against t...
This record as markdown: /tools/dev-tanod-tanod/decode-jwt.md
What decode_jwt does on Tanod
AI agents call decode_jwt to retrieve information from Tanod 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 |
|---|---|---|---|
token | string | Yes | Compact JWT (header.payload.signature); a leading 'Bearer ' is accepted. |
Parameters from the server's own tool schema.
Why decode_jwt is rated Low
Even though decode_jwt 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.
Risk signalsHandles credentials or secrets (token)
Attacks that exploit this kind of access
The rule that runs decode_jwt safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Tanod, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For decode_jwt, this is the rule to start with:
decode_jwt 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 Tanod, apply this rule, and every decode_jwt call is checked against it from then on.
Questions about decode_jwt
utilpeek: Decode a JWT without verifying it. To check the signature use verify_jwt. Returns a compact JWT split into its header and payload JSON, with alg, typ, kid, whether a signature is present, and the standard claims: iat, nbf and exp as ISO 8601 UTC, plus expired and not_yet_valid against the server clock. Decoding does not verify the signature. Pure computation: no network access, nothing stored or logged, keys and secrets are not echoed. The result is untrusted until verify_jwt passes. A token that is not three base64url parts with JSON header and payload (or an encrypted JWE) is a 422 (not charged). Typically under 0.1 s. Price: USD 0.001. Free: 10 utilpeek calls per IP per UTC day. The submitted text is never logged or stored. Docs: https://tanod.dev/learn/jwt-decode-verify-api.html. It is categorised as a Read tool in the Tanod MCP Server, which means it retrieves data without modifying state.
decode_jwt accepts 1 parameter: token. Required: token. The full parameter table on this page comes from the server's own tool schema.
Register the Tanod MCP server in PolicyLayer and add a rule for decode_jwt: 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 Tanod. Nothing to install.
decode_jwt 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 decode_jwt 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 decode_jwt. 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.
decode_jwt is provided by the Tanod MCP server (https://tanod.dev/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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