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

Annotations only declare it is a non-destructive write; the description goes well beyond that by disclosing that the new version lands as a draft and never replaces the active one automatically. It adds rate limits, runtime, credit cost, and the conditional return shape, which is exactly the behavioral context an agent needs before spending 300 credits.

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?

Well front-loaded: purpose, then draft semantics, then alternatives, then timing and returns. No filler sentences, but the final sentence is a dense run-on covering two return paths plus cost and credits, and 'Takes 45 to 70 seconds' sits awkwardly beside 'ready within about 40 seconds', which is a mild internal inconsistency.

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?

With no output schema, the description carries the return contract itself (brief_id plus draft, or brief_id to poll, plus cost and credits remaining) and covers the mutation's safety model. For a costly, rate-limited, long-running build tool, nothing an agent needs in order to call it correctly is missing.

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 'fresh' parameter already carries a detailed explanation of the 10-minute rebuild window and 90-second in-flight behavior. The description adds no parameter-level meaning beyond that, so the baseline of 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?

States a specific verb and resource ('Builds the Creator Brain from the creator's documents and profile') and defines the artifact produced: a checked brief of identity, offers, proof, pillars and voice rules. It explicitly separates itself from siblings get_creator_brain and activate_creator_brain, so an agent can route correctly without opening 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 an explicit sequencing rule ('Use it after add_brain_document') and names the alternatives with their selection conditions: get_creator_brain to read, activate_creator_brain to switch versions. It also states the practical constraints that shape when to call it (6 times a day, 45-70 seconds, 300 credits).

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