Project Add Costume

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

With no annotations, the description carries the full disclosure burden. It reveals two meaningful behavioral traits: the file is copied into the project's assets/, and the costume is appended last, becoming the highest costume number. It does not cover overwrite behavior, permissions, or failure modes, but it goes beyond simply restating the action.

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?

Two short paragraphs, front-loaded with the main action, then input modes, then the side effect and ordering. Each sentence contributes new information and there is no filler. The line break around the `file`/`svg` choice makes it scannable.

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 one required parameter, 100% schema coverage, and an output schema, the description provides enough to call the tool correctly: what to pass, which input form to use, and the side effect. It omits edge cases (both `file` and `svg` provided, or neither) and doesn't address sibling selection, but these are secondary.

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. The description adds value by explaining that `file` accepts .svg/.png/.jpg, that `svg` requires `name`, and that `name` defaults to the filename without extension. This coupling goes beyond the schema's bare descriptions.

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 states a specific verb ('Add') and resource ('costume to a sprite') and scopes it to 'the project's assets/'. This clearly separates it from asset-removal and sound siblings. However, it does not explicitly differentiate itself from the similarly named `sb3_add_costume`, leaving some ambiguity about which level (project vs sb3 VM) to use.

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 gives actionable guidance: use either `file` or `svg`, and that `svg` requires `name`. This resolves the main input ambiguity. It does not, however, mention when not to use this tool or when to prefer an alternative like `sb3_add_costume`.

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