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

With no annotations, the description carries the full burden and does well: it discloses the default omission of the catalog, the size cost, the presence of unacknowledgedComments on discussion hosts, and that a nonzero count carries a bounded comments notice. It stops short of stating permissions/auth needs or pagination/limits, so it is strong but not exhaustive.

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?

Front-loaded with the core purpose and return contents, then conditional behavior. Dense but every clause carries information; a couple of the later sentences are long, though none are filler.

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 not be detailed, yet the description still names the returned document parts and the conditional comments field, making the tool callable and interpretable. The only missing element is auth/permission context for a read against designs.

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 75%, and the description adds real meaning beyond it: it explains why includeCatalog defaults to false and where the catalog is served instead, and it frames the revision parameter by tying it to baseRevision quoting for edits. designId is trivial and token is documented in the schema, so the remaining gap is minor.

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 one design') and enumerates exactly what the read returns — nodes, slots, properties, modifiers, state variables, catalog pin, and the revision for baseRevision. This distinguishes it cleanly from ui_builder_list_designs and ui_builder_view without needing to open 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?

Gives clear conditional guidance for includeCatalog (omit the catalog by default because it is identical per pin and byte-heavy; use ui_builder_list_catalogs instead) and explains the baseRevision purpose for subsequent edits. It does not explicitly contrast against ui_builder_view or ui_builder_await_design, so no hard when-not guidance.

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