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 that every field is optional, that an all-empty reply means nobody has linked anything yet, and that the record lives beside the design — no node holds it, no export sees it, and writing one does not move the revision. That last point is exactly the non-destructive, side-channel behavior an agent needs. It never explicitly labels the operation as read-only, which keeps it from a 5.

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-loads the purpose in one clause, then moves to routing, then to isolation semantics — a sensible order with little waste. The backtick-heavy field enumeration and the run-on "no node holds it, no export sees it" triad are slightly padded, but each sentence 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?

An output schema exists, so return values need not be explained, and the description sensibly covers purpose, routing, optionality, and the record's isolation from the design document. Combined with the undocumented designId parameter and absent annotations, it is nearly complete but leaves that one parameter gap unaddressed.

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 only 50%: the token parameter is documented in the schema, but designId has no description anywhere, and the prose adds nothing about either parameter — it only describes the returned record fields. With half the parameters undocumented in both places, the description fails to compensate for the coverage gap.

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 (the links/brief record attached to a design), then enumerates exactly what the record contains (issue, reference frame, pr, thread, previous). It explicitly separates itself from the sibling ui_builder_get_design, so an agent can route without opening either 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?

"Start a session on somebody else's design here — it is the brief, and it is what ui_builder_get_design cannot tell you" gives a clear when-to-use condition and names the alternative. It stops short of an explicit when-not or of pointing at ui_builder_set_links as the write counterpart, so it is clear context rather than full routing guidance.

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