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

With annotations already declaring readOnlyHint=true and destructiveHint=false, the description adds substantial behavioral detail: geometric matching by wall endpoints, openings, and object type/position rather than index, so deletion does not cascade into false modifications. It also discloses the return structure field by field and item by item.

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 front-loaded with the WHEN condition and remains focused on the comparison logic and outputs. It is somewhat dense and could be split for readability, but every sentence contributes useful selection or behavioral context.

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?

Despite having no output schema and nested object inputs, the description explains the comparison method and the returned categories (added, removed, modified, quantity differences) sufficiently for an agent to understand what it gets back. Annotations cover the safety profile, and the schema covers input shapes.

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 100%, so the schema already documents avant, apres, and quantites. The description reinforces that quantites drives an item-by-item quantity take-off comparison, but adds little syntax or format meaning beyond what the schema provides.

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 states a specific verb and resource: comparing two versions of a building model. It also specifies the exact outputs (added, removed, modified elements plus quantity take-off differences) and explains the geometry-based matching, which distinguishes it from a naive index-based diff and from the sibling merge tool.

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?

It clearly says WHEN to use it: to see what a client, architect, or another agent changed and to derive the basis of a change order. It does not explicitly name alternatives or state when not to use it, but the usage context is clear and actionable.

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