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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds a genuinely useful behavioral trait beyond annotations: non-processed responses return empty facets rather than erroring, which tells the agent how to interpret an apparently-successful but empty result. No auth or rate-limit context, but none is expected for a read-only lookup.

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 sentences, no filler, and the empty-facets caveat lands at the end where it functions as a guard. The first sentence is a dense facet enumeration that is slightly heavier than needed given an output schema exists, but each listed facet is substantive rather than padding.

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?

For a single-parameter read tool with an output schema, annotations, and 100% schema coverage, the description supplies what the structured fields do not: the precondition for non-empty results and the provenance of the ID. Nothing needed to call it correctly is missing, though the facet enumeration partially duplicates the output schema.

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?

There is a single parameter with 100% schema description coverage, and the description's mention of insightId sourcing largely mirrors the schema's own description. Baseline 3 applies since the schema carries the parameter documentation and the description adds no format or constraint detail beyond it.

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 names the exact resource and scope: video-derived UX signals for ONE usability-test session recording, and enumerates the five facet families returned. An agent can tell this apart from sibling retrieval tools because it is explicitly tied to video-metadata extraction rather than raw response data. It stops short of explicitly contrasting itself with response_detail or responses_search beyond naming them as ID sources.

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?

It states the lookup key and where to get it (responses_search / recent_responses / response_detail), and gives a concrete precondition: only responses whose recording was processed by video-metadata extraction have this data, others return empty facets. That is a clear usage context. It does not spell out a 'use X instead when Y' branch for the ID-source siblings.

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