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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds two useful non-annotation facts: the call is free (no credit cost) and it returns the full style JSON rather than a summary. It says nothing about behavior for a missing id or whether brand presets are covered.

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 fragments with no filler, and the cost note plus the resource scope are front-loaded. The telegraphic style ('Free. One saved custom preset...') is efficient but slightly stenographic compared to a full sentence, costing a bit of readability.

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 one-parameter read tool with no output schema, the description covers the key unknowns: cost, id format, and that the full style JSON comes back. It is thin only on the not-found error path and on disambiguation from the preset-listing and style-reference siblings.

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 description coverage is 0% and the single id parameter carries no description at all, so the description is the only source of format information. It supplies the accepted id shapes (cp_... or custom:cp_...), which is exactly the missing operative detail for this one required param.

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 the specific resource (a saved custom preset) and scopes it to exactly one item fetched by id, which distinguishes it from list_custom_presets and list_presets. It does not name any sibling explicitly, so an agent must infer the single-vs-list split rather than being told.

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 "by id" phrasing implies this is the follow-up call once a preset id is known, but there is no explicit when-to-use vs when-to-use-instead guidance. No mention of what to do when the id is unknown (use list_custom_presets) or how this differs from get_style_reference or list_presets.

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