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

With no annotations provided, the description carries the full burden of behavioral disclosure. It clearly states that the tool mutates an existing layer, only changes the bitmap, preserves other layer properties, and does not upload the asset itself. It also warns about the downside of the alternative approach, giving an agent a realistic model of the tool's effects.

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?

The description is three sentences with no filler. The core behavior is front-loaded, followed by the prerequisite and then the use-case comparison. Every sentence adds necessary information for correct selection and invocation.

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?

Given the moderate complexity, lack of annotations, and absence of an output schema, the description is nearly complete. It covers the operation, the preservation semantics, the asset prerequisite, and why the alternative is inferior. It does not describe the response/return value or error behavior when the asset is missing, but this is a minor gap for a focused mutation tool.

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 the baseline is 3, but the description adds meaningful context beyond the schema: it explains the asset path structure (users/<userId>/assets/<projectId>/<filename>), clarifies that projectId selects which existing project is mutated, and ties filename to an already-uploaded asset. This goes beyond simply restating parameter names.

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 uses a specific verb ('Repoint') and resource ('an existing image layer at a different uploaded asset'), and clearly distinguishes the operation from sibling tools like add_image_layer and upload_image. It also explains what is preserved (id, position, size, animations, styles), so an agent can precisely understand the tool's scope.

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?

The description explicitly states when to use this tool: to swap a layer's image without losing keyframes. It names the alternative (remove_layer + add_image_layer) and explains why that alternative is worse because it would mint a new id and drop animations. It also provides the prerequisite that the asset must already exist and tells how it could have been uploaded.

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