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

Annotations already declare destructiveHint=true and readOnlyHint=false, so safety is partly covered. The description adds real behavioral value by clarifying the mutation is a PARTIAL SAVE that leaves all other v1/v2 fields untouched, reducing the perceived blast radius. It stops short of describing auth requirements or response behavior, so 4 rather than 5.

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 critical constraint ('PARTIAL SAVE: writes ONLY the ImageData field') is front-loaded, followed by dict semantics, then routing alternatives. Dense and front-loaded with no filler sentences.

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 mutation tool with a nested object parameter and no output schema, the description covers scope of the write, the shape and meaning of key/value pairs, and where to send related icon types. Nothing material is missing for correct invocation.

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 100%, so the baseline is 3, but the description adds genuine meaning: keys are project-defined slugs (with examples like 'main_banner') and values are URLs or storage paths. This is more than the schema's terse 'New value for the ImageData field.'

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 (writes/saves) and resource (the 'ImageData' field of TitlePublicConfigurationModel), and immediately scopes it as a PARTIAL SAVE. The reader can tell exactly what changes and can distinguish it from the broad get_image_data/save_title_data 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?

Explicitly routes the agent to alternatives: per-currency icons go to Currency.VirtualCurrencies[].AssetPaths, per-item icons to Item, character art to Character. Combined with the 'writes ONLY ImageData' constraint, both when-to-use and when-not-to-use are covered.

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