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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds the genuinely useful traits that results are returned in a defined order and that the IDs are exact/authoritative for follow-up queries. It says nothing about pagination, large test behavior, or what happens for a test with no runs, which keeps it at an adequate-not-rich 3.

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?

One tight sentence with the returned fields front-loaded and no filler. It is arguably too compressed rather than bloated, but nothing in it is wasted.

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 return values need not be narrated, and the safety semantics come from annotations. What is missing for a two-parameter query tool is the meaning of the optional runId and any prerequisite about test state, which leaves the definition minimally viable rather than complete.

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 0% for both parameters, so the description carries the full burden. It alludes to run vs. test scope but never explains what passing runId does versus omitting it, nor notes the 24-character hex ObjectId format the schema's pattern enforces. The agent is left to infer the relationship between the two IDs.

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 ('List ordered blocks') and enumerates the payload ('statuses and exact block/run IDs'), which is enough to distinguish it from list_tests, list_audiences and list_insights. The trailing phrase 'for result queries' is vague and never explains what a 'block' actually is. Clear, but without any explicit sibling differentiation.

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?

'for result queries' is the only usage hint, and it is too thin to route an agent between this tool and neighbors like get_test_definition, prepare_test_block or show_evidence. No when-to-use, no when-not-to-use, no prerequisites (e.g., whether the test must already be launched or have results).

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