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

With no annotations, the description carries the full burden, and it does disclose real behavioral traits: the return is a structured comparison table grouped by property, and the tool accepts only 2-5 IDs. It omits error behavior for invalid IDs and doesn't explicitly confirm the read-only nature, but for a comparison tool the disclosed behavior is largely sufficient.

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?

Three sentences, front-loaded with the usage trigger, then output shape, then input constraints. No filler, no repetition, and every sentence carries information an agent needs.

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, but the description compensates by describing the returned comparison table grouped by property, and it covers trigger, inputs, and limits. The only missing piece is failure behavior for unknown or mismatched material IDs, which keeps it from a 5.

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% and both parameters are documented there, including the default property list and the min/max item bounds, so the baseline is 3. The description restates the 2-5 range and the optional properties list without adding format or syntax meaning beyond the schema.

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?

Names a specific verb+resource ('compare materials') and anchors it with concrete examples ('AL6061 vs SS304', 'which plastic is stronger') that make the intent unmistakable against siblings like search_materials or find_equivalent_materials. It also states the output shape and accepted input range, so an agent knows exactly what this call produces.

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?

Opens with an explicit trigger ('Use when the user asks to compare materials'), which is clear when-to-use guidance. It stops short of naming alternatives or stating when NOT to use it (e.g. versus find_equivalent_materials), so it earns a solid 4 rather than a 5.

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