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

Annotations already declare readOnly/idempotent/non-destructive behavior, but the description adds a genuinely useful caveat beyond them: tool success does not confirm the client rendered the gallery. It also clarifies the reuse-the-same-arguments execution model, which is not visible in structured fields.

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 primary action, followed by the two constraints that matter. Nothing 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 no explanation. Combined with the render caveat and argument-reuse instruction, the description gives everything needed to call this display tool correctly.

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?

With only 50% schema description coverage, the description compensates by narrowing what belongs in arguments (test/run/block IDs, reuse of the read call's exact arguments) and the schema reinforces the 'no image bytes or URLs' constraint. The enum values for operation are left to the schema, so this is not a full 5.

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: display an inline screenshot gallery. An agent can distinguish this from the read siblings (get_insight, get_frame_details, get_screen_details) since it renders rather than fetches, though the description never names those siblings explicitly.

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?

Gives clear triggering context: use it after reading evidence, reusing the same operation and exact arguments. It does not enumerate alternatives or state when not to use it, so it falls short of a 5.

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