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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds one genuinely useful behavioral fact beyond that: missing data and timeout reason codes are not conclusive verdicts. It says nothing about latency, cost, or lookup failure modes.

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 front-loaded sentence with no filler; the core action is stated first and the caveat second. It is efficient, though the brevity comes at the cost of the detail the low schema coverage demands.

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?

An output schema exists, so return values need not be explained, and the tool is low complexity with one required parameter. However, with 0% schema coverage the description should at minimum identify the source of reason codes and note what happens when a code is unknown, which it omits.

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% and the single reason_code parameter has no title detail, so the description must carry the meaning. It only gestures at 'a sandbox reason code' without saying where the code comes from, whether it is free-form or an enum, or how to obtain one, leaving the parameter effectively underspecified.

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 pairs a specific verb (explain) with a specific resource (a sandbox reason code), which is enough to tell it apart from the verification-planning siblings. It stops short of naming which sibling produces the codes it consumes, so it is clear but not fully differentiated.

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?

There is no statement of when to reach for this tool versus plan_verification, get_coverage, or the sandbox verification tools. The only usage-adjacent content is the note that missing data and timeout are inconclusive, which is an output caveat rather than a routing rule.

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