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

Annotations already declare destructiveHint=false and openWorldHint=true, so the safety profile is partly covered, but readOnlyHint=false leaves ambiguity about whether this mutates state. The description resolves that by clarifying it only stages for review and 'Does NOT create anything', which is genuinely additive. It still omits permissions, idempotency behavior, and what staging produces (covered by the output schema), so it is not a 5.

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?

Two short sentences with the primary action front-loaded and the key non-behavioral fact ('Does NOT create anything') immediately after. No filler or repetition.

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 a 100% covered schema and an output schema present, the description needn't explain parameters or return values, and it correctly clarifies the non-creation semantics. However, for a propose-stage tool the critical missing context is the follow-up path (what applies the staged test, whether approval is needed), which the agent cannot derive from the structured fields alone.

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 100%, and each parameter already carries rich inline documentation (date constraints, cell structure, percent defaults, account override). The description adds nothing about parameters, so the baseline of 3 for a fully documented schema 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 and resource ('Stage a Meta A/B test (split test)') and adds the scope qualifier 'for review', so an agent understands this is a proposal operation. It stops short of naming the sibling that would execute the test (apply_change), so differentiation is implied rather than explicit.

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 explicit when-to-use guidance, no when-not guidance, and no named alternative such as apply_change or propose_change. 'Stage for review' hints at a propose-then-apply workflow, but the agent must infer which sibling commits the staged test.

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