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

Annotations only declare the generic mutation profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false). The description adds real behavioral context beyond that: the flow appears in the Miami builder immediately, the agent session is attached as a chat, and it returns a flow id plus a builder deep link. Still silent on permissions/org scoping and any rate or naming constraints.

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?

Purpose is front-loaded in the first clause, followed by behavior, parameters, and routing in a logical order. Slightly chatty in places ('It appears in the Miami builder immediately, with this agent session attached as a chat'), but no sentence is purely 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?

Covers the essentials for a 9-param creation tool with no output schema: what it creates, the immediate side effect, the return value (flow id + deep link), the get_scaffold prerequisite, and the start_build alternative. Gaps are minor — org/permission requirements and most optional theme knobs go unqualified.

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?

With schema description coverage at 33% across 9 params, the description should carry more weight. It does add useful framing for the theme group ('theme knobs seed the live palette') and clarifies `device` with examples and a cross-reference to set_flow_device, but title, agent, and the fonts/shape/theme nuance remain undocumented here. Partial compensation only.

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+resource ('Create a new, empty flow (app build)') and immediately scopes it as agent-authored ('for YOU to write the app into'). It distinguishes itself from siblings: 'empty' contrasts with flow_create_flow_from_blueprint, and the closing line names start_build as the different path for merely-described apps.

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?

Names an explicit alternative for one case ('For an app the user merely DESCRIBED, use start_build') and a prerequisite ('Call get_scaffold before writing files'). It implies but never explicitly excludes flow_create_flow_from_blueprint, so the when-not coverage is not fully complete.

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