Decode a JWT header and payload locally offline, inspect claims like exp, iat, nbf, sub, and iss, and check expiration status without network calls.
Decode a JSON Web Token (JWT) header and payload locally offline without external network calls, inspecting claims (exp, iat, nbf, sub, iss) and expiration status.
| Name | Required | Description | Default |
|---|---|---|---|
| token | Yes | Encoded JWT string (header.payload.signature) |
Changes observed during successful MCP inspections.
v1.3.4Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, openWorldHint=false, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description usefully reinforces the offline/no-network behavior and names the claims inspected, but it never states the key limitation that this is a decode-only operation with no signature verification.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single sentence with the core action front-loaded and zero filler; the offline constraint and inspected claims follow in a natural reading order.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
With no output schema, the description does carry the burden of indicating what comes back, and it lists the extracted claims (exp, iat, nbf, sub, iss) plus expiration status. It is nearly complete for a one-parameter tool, missing only the caveat that no signature validation occurs.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% and the single parameter 'token' is fully documented in the schema as header.payload.signature, so the schema does the heavy lifting. The description adds no format or syntax detail beyond that baseline.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description names a specific verb (Decode) and resource (JWT header and payload), and no sibling tool (hash, secret, scan_secrets, cidr, etc.) overlaps with JWT decoding, so the tool is trivially distinguishable. It also scopes the operation as a local, read-only inspection.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Usage is implied: decode a token to inspect its claims and expiration. There is no explicit when-to-use statement, no exclusions, and no named alternative, though none of the siblings is a plausible substitute, which limits the cost of the omission.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.