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

Annotations already cover readOnly/idempotent/non-destructive, and the description adds useful context beyond them: thresholds are parsed from regulation records, the source record ID is returned with each row, and the tool is deliberately scoped to one material. It doesn't discuss error behavior or precision/rounding, so not a 5.

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?

Front-loaded with labeled Purpose/Guidelines/Limits and a concrete example, so an agent can parse it quickly. It is dense but every sentence earns its place; the embedded example is slightly redundant with the schema but aids invocation.

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?

With an output schema present, return values needn't be explained, and the description covers scope limits plus the returned source record ID. For a read-only calculation tool the description is essentially complete, with only minor gaps around edge cases (e.g. out-of-range current_pct).

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 coverage is 100% and enums are fully documented, so the schema already carries parameter meaning. The description restates material options and current_pct usage but adds no format or constraint detail beyond the schema; 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?

States a specific verb (compare/calculate gap) and resource (recycled-content figure vs statutory minimum), scoped to one material and both stages. This is clearly distinguishable from siblings like get_recycled_content_requirements and query_battery_recycling_targets, which fetch requirements rather than compute a gap.

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?

Explicitly says to supply material and current_pct, and adds strong negative guidance: one material at a time, NOT a whole-battery compliance finding, not advice or a declaration basis. It lacks a named alternative sibling (e.g. where to go for whole-battery compliance), which keeps it from a 5.

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