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

Annotations already declare readOnlyHint=true, idempotentHint=true, 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 but vague — it never says what the defaults actually are.

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?

Three short sentences, front-loaded with the purpose before the targeting details. 'Legacy tests also supported' is a slightly tacked-on fragment, but nothing is redundant or padded.

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 and full read-only annotations mean return values and safety need not be re-explained. The remaining gap is orientation: with get_human_navigation_summary as a sibling, the definition should say which summary applies to which test type, and it doesn't.

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 only 33% (only blockId is documented inline), so the description must compensate. It partially does, telling the agent where IDs come from (list_test_blocks) and that omission is safe, but it says nothing about runId or the required 24-hex testId beyond the schema's pattern.

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: 'Read aggregate navigation and completion metrics.' Clear about what it returns, but it does not distinguish itself from the near-identically named sibling get_human_navigation_summary, leaving the agent to guess which audience (simulated vs. human) each summary covers.

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' gives context for obtaining inputs, and 'Legacy tests also supported' hints at an edge case. However, there is no explicit when-to-use/when-not guidance and no routing to the alternatives (e.g., get_human_navigation_summary) that share this tool's space.

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