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

Beyond the annotations (readOnly=false, idempotent=true, destructive=false), it discloses two non-obvious behaviors: the crop is re-cut from the original source image rather than the current crop, and already-created plans retain the old piece. It leaves partial-update semantics (are unspecified fields preserved?) unstated.

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, waste-free sentences with the editable fields front-loaded and the two behavioral caveats following. Nothing is repeated from the schema or annotations unnecessarily.

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 five-parameter mutation tool with a nested crop object, no output schema, and annotations covering safety, the description supplies the behavioral quirks an agent cannot infer. Missing only the return value hint and whether this is a partial patch or full replacement.

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?

With only 40% schema description coverage, the description compensates by naming each mutable field (name, handle, description, crop) and clarifying that crop is measured against the source image the piece came from. It does not explain that description accepts null to clear it, which the schema's anyOf implies but never 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?

The description names the concrete mutations available (rename, handle, description, re-crop) on the implied kit piece, so the agent knows exactly what the tool changes. It does not explicitly differentiate itself from siblings like add_kit_piece, delete_kit_piece or get_kit_piece.

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: it is clear this is the edit path for an existing piece, but there is no explicit 'use this instead of X' routing, no precondition (e.g. owning the kit), and no statement of when not to use it. The note about existing plans is a side effect, not selection guidance.

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