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

Annotations already cover the safety profile (read-only, idempotent, non-destructive), so the description adds useful behavioral context by naming the false-positive-rate calculation, an example value, and the boundary families. However, it does not reconcile the 'up to 10 equally spaced looks' statement with the schema's maximum of 50, leaving a behavioral limit ambiguous.

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 front-loaded and contains no filler, but it packs multiple outputs and a constraint into one dense sentence, reducing scanability slightly.

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 two-parameter read-only computation with no output schema, the description names the returned quantities and boundary types, so an agent knows what to expect. It still leaves the output structure and the 10-vs-50 looks limit ambiguous.

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 coverage is 100%, and the schema already documents alpha and looks. The description reinforces the meaning of repeated looks and gives an example at alpha 0.05, but the phrase 'up to 10 equally spaced looks' conflicts with the schema's maximum of 50 for looks, which can confuse parameter validity.

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 specifies the computed quantities: the real false positive rate under repeated checks and Pocock/O'Brien-Fleming sequential boundaries. It is clearly about peeking/sequential-testing risk, but it does not explicitly distinguish this from sibling tools such as test_ab_significance or calculate_sample_size.

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?

No sentence states when to use this tool versus the sibling significance or sample-size tools. The peeking-risk framing implies a planning or repeated-checking use case, but the agent must infer that and may confuse it with test_ab_significance.

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