design_set_blend_mode

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

No annotations are provided, so the description carries the full behavioral burden. It implies mutation but does not state whether the layer must already exist (only 'existing layer' hints at it), what happens on an invalid layerId, whether the change is undoable, or what is returned.

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?

A single front-loaded sentence with no filler. It is efficient, though its brevity is partly under-specification rather than deliberate economy.

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 two-parameter tool with a fully documented enum and no output schema, the description is minimally sufficient. Missing are the mutation semantics (confirmation, reversibility, failure behavior) that no annotation covers.

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 enum enumerates all valid modes, so the schema does the heavy lifting. The description adds only the mild constraint that the target layer must already exist; it does not explain how to obtain a layerId.

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 ('Set') and resource ('blend mode') scoped to 'an existing layer', which is enough for an agent to distinguish it from design_list_blend_modes (read) and design_update_layer (generic mutation). It stops short of naming those siblings 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?

No guidance on when to use this versus design_set_blend, design_update_layer, or design_list_blend_modes for discovering valid modes. The agent must infer the routing decision entirely from tool names.

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