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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the safety profile is carried structurally. The description contributes the prerequisite that the test must be running, but it never explains that the change diverts live traffic immediately, whether the adjustment is reversible, or what a failed adjustment leaves behind — meaningful gaps for a destructive operation.

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 ten-word sentence, front-loaded with the action and the constraint. There is no filler, hedging, or restatement of the tool name.

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?

The tool is simple (two required parameters, flat schema) and annotations cover the safety profile, so the description is close to sufficient. However, there is no output schema, so the agent has no idea what a successful adjustment returns, and a destructive mutation of live traffic deserves at least a note on effect timing and reversibility.

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%: groupId is documented as a policy group ID and trafficRate as a 1-99 challenger traffic percentage, including bounds. The description adds only the framing that the rate belongs to a running test and does not clarify whether trafficRate is absolute or a delta from the current rate, which is the ambiguity the schema does not resolve.

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 uses a specific verb ("Adjust") with a specific attribute ("traffic rate") of a specific resource ("a running A/B test"), which separates it from siblings like lexq_ab_test_start and lexq_ab_test_stop. The word "running" adds a state qualifier that further narrows intent, though it never names the sibling tools it contrasts with.

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?

"Running A/B test" implicitly tells the agent this applies only to an already-started test, so start/stop are the implied alternatives. There is no explicit when-not guidance, no statement about what happens if the test is stopped or absent, and no routing language naming the sibling tools.

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