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

The description adds meaningful behavioral context beyond the annotations: it indicates the operation issues a 'signed' and 'point-in-time' artifact, and requires explicit opt-in. This is consistent with readOnlyHint=false and destructiveHint=false. It does not cover failure modes or side effects, but given the annotations already provide safety signals, the description adds sufficient nuance.

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 two concise sentences with zero fluff. The first sentence states purpose and condition; the second clarifies exclusions. Information is front-loaded and every word earns its place.

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 one parameter, no output schema, and annotations present, the description covers purpose, condition, and exclusions. However, it does not describe the output format (e.g., the passport structure) or potential error conditions (e.g., what happens if the domain does not opt in). For a tool that issues a credential, these are notable omissions.

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 description coverage is 0%, so the description must compensate for the undocumented parameter. The description implies agentCardUrl is the agent's domain URL (since it references the agent's own /.well-known/naif-trust.json), but it does not explicitly state what agentCardUrl represents or how it relates to the opt-in mechanism. This leaves the parameter under-explained.

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 clearly states the action ('issue'), the resource ('signed point-in-time technical passport'), and the condition (agent domain explicitly opts in via its own /.well-known/naif-trust.json). It also explicitly disclaims what it is not ('not a ranking, endorsement, or security audit'), which helps distinguish it from potential siblings like verify_trust_token.

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 provides a clear precondition for use (the agent domain must explicitly opt in) and clarifies the tool's non-purpose (not ranking, endorsement, or audit). However, it does not explicitly name alternative tools or state when not to use it beyond the opt-in condition, leaving some routing to inference.

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