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

Annotations already flag destructiveHint=true/readOnlyHint=false, so the safety profile is covered. The description adds substantial behavioral context beyond them: darkUrl defaults to url, the light/dark choice is driven by the section's ACTUAL paint and is what the export ships, and no stored colour is read by canvas or export. It never mentions that an existing logo is overwritten, which is the one gap.

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?

The purpose and default scope are front-loaded in the first clause, and the partner-logo and colour exclusions each earn their space. It is dense and dash-heavy, with some phrasing ('the same answer the canvas reaches, and that per-slot choice is what the export ships') that could be tightened, but little is pure padding.

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 6-parameter, nested-object tool with no output schema, the description covers the semantics that matter most (site vs partner slot, light/dark pairing, scale, colour exclusion). The `theme` parameter is not explained in the description, but the schema handles it and the remaining surface is well covered.

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 83% (baseline 3), and the description meaningfully extends it: `darkUrl` is described as the light-coloured mark for dark-painted sections defaulting to `url`, `scale` is framed as the panel slider (0.5-2, 1 = as designed), and `slot` is defined as a single client/partner slot from uichemy_get_logo. Only `theme` is left entirely to the schema.

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 ('set' the site's logo) and immediately scopes it: by default it paints the logo on every navbar/footer/404 mark, or with `slot` it targets ONE partner logo slot. It cleanly distinguishes itself from uichemy_get_logo (which lists slots) and uichemy_upload_image (which yields a url), so an agent can tell it apart from siblings.

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?

Gives explicit routing: use `slot` only for a content section labelled as a client/partner mark, use uichemy_get_logo to list slots, and uichemy_upload_image to obtain a url. It also states an exclusion ('There is no logo COLOUR to set'). It stops short of a crisp when-not-to-use statement, but the context is clear.

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