Edit sprite

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

Annotations already declare the non-read-only, non-destructive, non-idempotent profile, and the description genuinely adds to that: 'The source file is never changed' tells the agent edits are written to a new output rather than mutating input, and the preserve_palette default is disclosed. It does not cover where output lands or how variants interact.

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?

Four short sentences, each carrying distinct information, with the core action front-loaded. No filler, though the default-behavior notes could be consolidated.

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 10-parameter tool with zero schema descriptions and no output schema, the description is thin: it never says where results are written, how 'variants' produces multiple outputs, what 'background' modes do, or how 'palette' relates to 'preserve_palette'. An agent could call it but would be guessing on most options.

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 0% across 10 parameters, so the description carries the full burden, but it explains only two behaviors: width/height defaulting to source dimensions and preserve_palette defaulting true. Seed, palette, variants, background (the sole enum), output_dir, and prompt semantics are all left undocumented.

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: 'Edit an existing sprite with an instruction.' It clearly distinguishes the operation from generating or transforming a sprite, though it never names the siblings (generate_sprite, inpaint_sprite, rotate_sprite) that an agent would choose between.

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?

Usage is only implied: 'existing sprite' suggests this is the tool for modifying an already-created asset. There is no explicit statement of when to prefer it over inpaint_sprite or rotate_sprite, nor any prerequisites (e.g., the file must exist).

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