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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description's real contribution is enumerating the returned fields (id, status, is_control, raw_contents) and explaining that raw_contents is a JSON field-key-to-value object, which is useful given there is no output schema. It says nothing about ordering or pagination for large variant sets.

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 dense sentence with the action front-loaded, the scope clarification immediately after, and the return fields appended. No filler, and every clause carries 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?

For a one-parameter read tool with annotations covering safety and no output schema, the description supplies the missing piece an agent needs: what comes back and in what shape. Nothing required to invoke it correctly is absent.

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 100% and the single surface_id parameter is documented in the schema, including its provenance (from surface_list). The description only implies that the listing is scoped to a surface, adding no format or edge-case detail beyond the schema, so the baseline 3 applies.

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?

"List every variant of a surface" gives a specific verb and resource, and "the control included" clarifies scope in a way that separates it from the mutation siblings (variant_create, variant_set_control). It stops short of naming an alternative tool explicitly, so it is clear but not fully differentiated.

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?

The read-only listing purpose implies when to reach for it (inspecting variants before mutating one), but the description never states when to use this versus surface_get or the variant_set_* tools. Usage must be inferred from the tool name and sibling names.

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