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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds that the token being renewed is read-only, but says nothing about token lifetime, whether the old token is invalidated, or rate limits on renewal — notable gaps for a credential-issuing operation.

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 dense sentence with zero filler that front-loads the consumer and the action. Nothing could be removed without losing information.

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 one-parameter, fully documented, annotated tool with no output schema, the description covers what it does and who uses it. It could go further by explaining the renewal trigger and what a successful call returns, but the essentials are present.

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?

There is one parameter with 100% schema description coverage, and the schema explains it fully ("The ref from an inspect_cad result whose preview token should be renewed"). The description adds no parameter-level detail, which is acceptable but not value-adding, 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 names a specific verb (renew) and resource (read-only preview token) and identifies the consumer (CADProps preview), so an agent knows exactly what the tool does. Sibling tools (convert_cad, inspect_cad, open_in_workspace) are unrelated, so no explicit differentiation is needed, though none is offered.

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?

"Used by the CADProps preview" implies the tool is scoped to that internal workflow, which indirectly signals it isn't a general-purpose call. However, it never states when the token should be renewed (e.g., on expiry/401) or what to do instead, leaving the trigger condition to inference.

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