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

Annotations declare this is a non-read-only, open-world, non-idempotent write, and the description adds the context they cannot: it takes about a minute, it produces an image plus a PNG link, and the file is also saved on the host device. Latency and a host-side side effect are exactly the traits an agent needs before invoking.

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?

Four short sentences, front-loaded with what is produced and at what size, then how to supply the input, then duration and return. Nothing is repeated from the schema and every sentence carries distinct 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?

A write tool with five parameters and no output schema, and the description covers duration, the returned artifact, the PNG link, and the host-device copy — everything needed to call it and act on the result.

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 is 3, but the description adds a constraint the schema cannot express: title plus summary is only used 'when there is no draftId,' clarifying the schema's implicit either/or despite only project being required. It also notes the brand's saved style still applies when styleIntent is given.

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 ('Creates a featured (hero) image in Hi, Moose') plus concrete scope details — 1200x630, for social sharing and the page, in the brand's saved image style. An agent can distinguish this from create_draft or create_audio 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 explicit input alternatives — 'Pass the draftId returned by create_draft, or a title plus a short summary' — which is real routing guidance for a tool with a conditional required set. It does not state when this tool should be skipped or what it replaces, so it falls short of full when/when-not guidance.

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