Verify a JWT token's signature and expiration to confirm authentication validity, rejecting invalid or expired tokens before accessing protected resources.
Verify a JWT token's signature and expiration
| Name | Required | Description | Default |
|---|---|---|---|
| token | Yes | JWT token to verify |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Without annotations, the description carries the burden of behavioral disclosure and does state the verification scope (signature and expiration). However, it omits outcome behavior—what happens for invalid, expired, malformed, or valid tokens—and any side effects, so the disclosure is incomplete.
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?
The description is a single, front-loaded sentence with no filler or redundancy. Every word adds information, making it easy to parse quickly.
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?
Given the tool's low complexity and one documented parameter, the description is broadly adequate. Still, with no output schema and no mention of return/error behavior, an agent cannot be fully certain how to interpret the verification result.
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?
The input schema already describes the single token parameter with 100% coverage. The description adds semantic framing by mentioning signature and expiration, but it does not meaningfully extend the parameter-level meaning beyond the schema, so the baseline 3 applies.
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 uses a specific verb ('verify') with a concrete resource ('JWT token') and states exactly what is checked: signature and expiration. This clearly differentiates it from sibling tools like decode_token, which parses rather than validates.
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?
The description implies the tool should be used when a token's authenticity/validity needs to be confirmed, but it provides no explicit when-to-use or when-not-to-use guidance. It does not name alternatives or exclusion conditions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.