gimp_select_by_color

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

Annotations declare readOnlyHint=false, destructiveHint=false, openWorldHint=false, so the safety profile is partly covered. But the description omits the most behaviorally important fact: the 'operation' parameter (replace/add/subtract/intersect) determines whether the existing selection is destroyed or combined, and nothing about scope (whole image vs. layer, sample_merged) is disclosed.

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?

Very short and front-loaded, with no wasted sentences. The terseness comes at the cost of completeness rather than being elegant brevity.

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?

A 9-parameter, selection-mutating tool with no output schema and 0% schema coverage needs considerably more explanation than three abbreviated sentences, particularly around the operation enum and image/layer targeting.

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 9 parameters, so the description carries the full burden. It explains only threshold (0-255), contiguous, and the color vs. x,y distinction, leaving operation, sample_merged, image_id and layer_id entirely unaddressed in both schema and description.

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+resource ('Selecciona por color') and usefully distinguishes two invocation modes (by color vs. by x,y magic wand). However it never differentiates itself from close siblings like gimp_select or gimp_modify_selection, so an agent cannot tell when this is the right selection tool.

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?

It gives conditional guidance for the two input modes ('Con color...' vs 'Con x,y...'), which is genuinely helpful. It stops short of any when-to-use vs. alternatives guidance relative to the many selection-related siblings.

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