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

Beyond the destructiveHint=true annotation, the description discloses the precise destruction semantics ("a pillar left out is removed") and the id-based edit-vs-create contract. It also covers target scope (active Brain vs. a given draft brief_id), the side effect that new drafts use the change at once, the return value, and the zero-credit cost — none of which the annotations convey.

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 action, then the list contract, then routing, then scope/cost. Every sentence carries distinct information — even the short trailing "Uses no credits" materially affects whether an agent should call estimate_cost first.

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 compensates by stating the return ("the saved pillars with what changed"). Combined with the replacement contract, prerequisite read, draft-vs-active targeting, and cost, an agent has everything needed to invoke this destructive mutation 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?

Schema coverage is 100%, so baseline would be 3, but the description adds a semantic the schema does not: this is a full-list replacement where ordering is significant and omission equals deletion. The per-field id/angle/shape/leads_to behavior is largely already in the schema descriptions, so the added meaning is real but concentrated in the list-level contract.

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?

The description opens with a specific verb and resource ("Sets the content pillars of the creator's Creator Brain") and enumerates the exact operations supported: rename, reword, add, remove, reorder. It also states the hard cap (up to 6), which immediately separates it from sibling tools like update_creator_profile or add_brain_document.

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?

It gives an explicit trigger ("Use it when the creator wants different topics") and a prerequisite ("read the current pillars and ids with get_creator_brain first"). It then routes away to the correct alternatives for adjacent needs — add_brain_document plus build for offers/proof/voice rules, and update_creator_profile for name, bio and niche — so the agent has a complete decision tree.

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