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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the read-only safety profile is covered structurally. The description adds the implicit constraint that the two images must be the same scope, which is real behavioral context, but says nothing about computational cost, failure modes, or what happens when scopes mismatch. With annotations doing the heavy lifting, a 3 is appropriate.

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?

A single compact sentence-pair that front-loads the platform context and then the three comparison outputs. Every clause carries content, though the headline-style noun phrase is slightly clipped and could read more cleanly as a sentence.

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?

There is no output schema, so the description correctly carries the return semantics itself, naming the three results (differing items, cell count, largest difference). Given a 3-parameter nested-object tool, this is nearly sufficient; a note on how differences are defined (byte vs scaled value) would close the remaining gap.

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 67% and the schema itself explains xdf_file (which .xdf variant per read size) and image_file (24 KiB window vs 512 KiB full flash), so the baseline is 3. The description adds only the 'same scope' constraint tying image_file and other_file together, and never mentions xdf_file, whose role in the comparison is non-obvious. No meaningful compensation for the uncovered portion.

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 names a specific verb+resource (compare two SMG II calibrations) and enumerates what the comparison yields: differing items, cell counts, and largest difference. This clearly separates it from read_oriented siblings like smg2_read and smg2_image. It stops short of naming any sibling by name, so it is not fully self-differentiating.

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 phrase 'two images of the same scope' implies a precondition (both files must be the same read scope), which is the only usage guidance offered. There is no explicit statement of when to use this versus smg2_read or smg2_image, and no exclusions or alternatives are named. Usage is left to inference.

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