set_custom_tile_data

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

Annotations already communicate that the operation is a safe mutation (readOnlyHint=false, destructiveHint=false). The description adds minimal behavioral context by specifying 'specific tile cells', implying a scoped change, but does not discuss effects like overwriting existing data, return values, or required preconditions.

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 description is a single, clear sentence that immediately communicates the core function. There is no unnecessary wording or ambiguity; every word contributes to understanding the tool's purpose.

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?

While the description and schema together cover the 'what' of the operation, the tool is a mutation with no output schema and no mention of return behavior or preconditions (e.g., whether the TileMapLayer or custom data layers must exist). This leaves some context gaps for an agent evaluating side effects or follow-up actions.

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?

The input schema provides 100% coverage with descriptions for every parameter, including the nested structure of 'cells'. The description adds little beyond restating 'specific tile cells', so the schema carries the heavy lifting. Baseline 3 is appropriate.

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?

Describes a specific action: setting custom data layer values on tile cells in a TileMapLayer. The verb 'set' and resource 'custom data layer values' clearly indicate the operation, and it is semantically distinguished from sibling 'set_cells', though it does not explicitly name alternatives.

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?

Provides no guidance on when to use this tool versus alternatives. The description only states what it does, not the context or conditions under which it should be preferred over similar tools like set_cells or get_tile_data.

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