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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint false), and the description reinforces this with 'Read-only; changes nothing'. It goes further by disclosing the return payload in the absence of an output schema: size, cropping/covering, layer format, the moves, the quality bar and the hand-off to the user. It omits auth, freshness or rate-limit context, so not a full 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-loaded with the usage condition, followed by the return contents, then a terse safety confirmation. The second sentence is long and list-heavy, but each clause describes a distinct part of the returned recipe and none is 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?

For a read-only, single-parameter lookup with no output schema, the description carries the full burden of explaining what comes back and does so thoroughly (size, crops, layer format with phone frames, moves, quality bar, hand-off). An agent has everything needed to call it correctly and to know what to do with 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 description coverage is 100% with a fully enumerated single parameter, so the baseline is 3. The description adds value by mapping human intents ('an animated product page header', 'a search result', 'In-App Event art', 'a launch post for X, LinkedIn or Instagram', 'a link preview', 'a Play feature graphic') onto the enum values, helping the agent pick the right asset string.

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 — returns the appdesigns recipe for a named asset as markdown — and enumerates the asset classes it covers (App Store header, search result, In-App Event art, social/marketing images). It also distinguishes itself from the sibling create_design by describing the recipe as 'the layer format create_design takes', so an agent can tell the two apart 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?

Gives a clear triggering condition: use it when the user wants listing art or a marketing image designed 'and you will draw it yourself', i.e. the agent renders the asset rather than having a tool do it. It never states an explicit exclusion or names create_design as the follow-up call, so the routing is implied rather than spelled out.

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