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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds that omission falls back to documented defaults and that legacy tests are supported, which is useful context, but it says nothing about result size limits, pagination, or error behavior beyond what the annotations and schema already convey.

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 tight sentences with the core purpose front-loaded ahead of the targeting guidance; nothing is padded. The trailing fragment 'Legacy tests also supported' is slightly disjointed but still earns its place by flagging a compatibility case.

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?

An output schema exists, so the description is not obliged to explain return values, and the annotations cover the safety profile. Still, for a 4-parameter tool with 25% schema coverage, the required testId and the limit parameter's semantics are unexplained anywhere, leaving the definition adequate but with visible gaps.

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 only 25% (only blockId is documented), so the description must carry weight: it explains block/run targeting via list_test_blocks IDs and the omit-for-defaults behavior, which covers blockId and partially runId. It never explains the required testId or what limit controls (default 8, max 20), so the low-coverage gap is only partially closed.

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 states a specific verb and resource ('List screens where participants stopped progressing') and even describes the ranking and included metrics, so the purpose is unambiguous. It does not explicitly differentiate itself from near-neighbors such as list_insights, list_paths, or list_screen_metrics, so it falls 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?

'Use IDs from list_test_blocks to target a block/run; omission uses the documented defaults' gives real prerequisite guidance and points at the sibling that supplies IDs. However, there is no statement of when to prefer this tool over list_insights/list_paths, nor any exclusion or precondition beyond that, leaving usage implied.

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