compare_volumes

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

The description discloses key behaviors: resampling of volume b onto a's grid if grids differ, and that the result is added to the session. Without annotations, this is valuable behavioral context.

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 extremely concise with a clear front-loaded purpose, followed by precise parameter explanations. Every sentence adds value without repetition or fluff.

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?

The description sufficiently covers the tool's behavior for a neuroimaging context, but could be slightly more complete by noting the output's data type or that it becomes available for subsequent operations. However, the absence of an output schema is mitigated by the 'adds to session' statement.

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?

Despite zero schema description coverage, the Args section provides full semantic meaning for all four parameters: 'a' is minuend/numerator and output grid, 'b' is second volume with resampling note, 'method' lists options, and 'name' is a handle. This completely compensates for the schema gap.

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 clearly states it performs voxelwise difference or ratio between two volumes and adds the result to the session. It specifies 'Arithmetic, not inference,' effectively distinguishing it from statistical tools in the sibling list.

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 description gives important usage guidance by saying the output is not a statistical map and should be described as a difference image. It does not explicitly mention when not to use or alternatives, 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.