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

Annotations already establish read-only, idempotent, non-destructive, non-open-world behavior, and the description adds genuinely new context: opening performs no evaluation, consumes no attempt, triggers no payment and no automatic retry. That side-effect profile is exactly what an agent needs before calling. It stops short of saying what the form returns or requires.

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?

Three short sentences, each carrying distinct information: what it does, what it does not do, and the fallback path. The most decision-relevant constraint (no evaluation, no attempt consumed) is front-loaded.

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 zero-parameter UI-opening tool with no output schema, the description covers purpose, side-effect costs, and the no-UI alternative. The only gap is what opening actually yields (URL, form id, or nothing), which the agent may need for follow-up.

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?

The tool takes zero parameters, so the baseline is 4. The {answer,sources} payload mentioned belongs to the sibling review_answer, not to this tool, so there is no parameter semantics to add here.

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?

States a specific verb and resource: 'Open an optional form to review an AI answer with your supplied source excerpts.' It is clearly distinguishable from the sibling review_answer, which it names. The only softness is what 'optional form' concretely is, but the action itself is unambiguous.

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?

Explicitly names the alternative and the condition that selects it: 'Without UI support, call review_answer with {answer,sources}.' This is a when-not-to-use-this rule plus the fallback tool and its arguments, leaving nothing to inference.

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