Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond annotations, the description discloses the paid nature (300 micro-dollar credits), the prerequisite of agent_utilities_prepare, auth requirements, and the billing/recovery semantics of requestId. This meaningfully enriches the annotations and helps the agent anticipate side effects and required setup.

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 compact yet information-dense, front-loading the core purpose before billing and usage warnings. Every sentence earns its place, and no wording is redundant.

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?

For a paid, externally-dependent tool, the description covers prerequisites, cost, authorization, idempotent recovery, and the key functional limitation. Since an output schema is present, the description does not need to explain return values, so nothing essential is missing.

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 67%, and the description adds semantic value by mapping 'optionally compare timestamps' to the atUnixSeconds parameter and explaining that a new requestId is a new billable operation. It also reinforces that maxPriceMicroUsd is a debit cap, which complements the schema's description.

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 opens with 'Decode untrusted JWT claims and optionally compare timestamps', which names a specific verb, resource, and action. It also clarifies what the tool does not do ('never verifies a signature'), distinguishing it from signature-focused JWT or security tools.

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 gives concrete usage context: call agent_utilities_prepare first, require existing credits and a private Authorization header, and reuse requestId for recovery. It does not explicitly name alternative tools or state when not to use it, but the 'never verifies a signature' caveat strongly implies the limitation.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.