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

Annotations already declare destructiveHint=true, idempotentHint=false, and openWorldHint=true, and the description adds no context on what gets overwritten, whether the session design is mutated, or auth/capability implications. The only behavioral content is the otherwise opaque warning about confusing an upload with an existing-image edit target.

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?

Three short sentences with no filler, and the core action is front-loaded. The final sentence is terse to the point of being hard to parse, which costs a point.

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 destructive, open-world mutation with a large aliased options object, the description is thin: it neither warns about side effects on session content nor explains the placement/coordinate options that distinguish correct calls. Schema coverage compensates for parameters, keeping it at minimum-viable rather than inadequate.

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 nested placement/asset semantics are documented in the schema itself, so the baseline of 3 applies. The description adds nothing about the very large options surface (coordinates, scale, placement spaces, asset reuse) beyond what the schema states.

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: adding uploaded or existing artwork to an area. This clearly separates it from add_text, add_keyline, and replace_image in concept, though it never names a sibling explicitly.

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?

'Use the returned asset or the supported imageFile transport' gives a routing hint for two input paths, and the last sentence hints that this is not the same as an existing-image edit (replace_image). However, no sibling is named and no explicit when-not conditions are given, so selection still requires inference.

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