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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds genuinely useful context: up to three screenshot previews are included, images may be unavailable, and legacy tests are supported. It does not mention pagination or rate limits, but adds real behavioral detail beyond the structured hints.

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?

Four short sentences, front-loaded with purpose before caveats and alternatives. The 'Legacy tests also supported' clause is slightly orphaned but every sentence carries usable 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?

An output schema exists, so return values need no explanation, and the description covers previews, image unavailability, and block/default behavior. Gaps remain on runId/testId semantics given the thin schema coverage, but for a read tool it is close to 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 only 25%, so the description must compensate. It adds meaning for ref (comes from list_insights) and blockId (target a block/run, omit to use defaults, legacy), but says nothing about runId or testId semantics. Partial compensation, so a baseline 3.

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 (Read) and resource (a finding by exact ref) plus scope (including evidence). It explicitly ties the ref to list_insights and distinguishes itself from get_frame_details, so an agent can pick it apart from siblings without opening a schema.

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?

Names an explicit alternative for the adjacent need ('Use get_frame_details for additional frames') and clarifies how blockId targeting works versus omission ('uses the documented defaults'). No explicit when-not-to-use beyond the frame case, so it falls short of a full 5.

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