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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description earns credit for the extra disclosures: it returns null when no experiment exists and 'never invents uplift,' which tells the agent how to interpret empty states and that figures are measured rather than modeled. It omits any note on freshness or how the 'latest' experiment is selected, keeping it from 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 zero filler, leading with what is returned and following with the null/empty-state caveat. Every sentence carries 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?

With no output schema, the description must convey return content, and it names the fields returned plus the null case, which is enough for a single-parameter read tool. It could say slightly more about the shape of 'sample sizes' or the notion of 'latest,' 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?

Only one parameter and schema coverage is 100%, with the schema already explaining that campaignId comes from list_programs. The description adds nothing further about the identifier, 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?

States a specific verb and resource plus the payload it returns ('latest holdout experiment, its sample sizes and measured return rate'), so the agent knows exactly what it retrieves. It does not explicitly distinguish itself from nearby siblings like get_streak_performance, so it stops short of a 5.

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?

The description says what is read but never says when to reach for it or when to prefer an alternative sibling such as get_streak_performance or get_goal. Usage is only inferable from the resource name, and no exclusion or precondition is offered.

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