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

Annotations already establish readOnly/idempotent/non-destructive, and the description adds substantial context beyond them: unreadable values become open cases rather than false 'unchanged', other device classes are refused, and it discloses its own validation limits ('a real pair with an actual value change has not been tested yet'). This is unusually candid behavioral disclosure.

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 the trigger and reads as information-dense rather than padded, but it is one long run-on paragraph whose validation statistics and nested scope/limitation clauses make it heavy to scan. Every sentence earns its place, yet tighter structuring would improve it.

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-format details are unnecessary, and the description still covers scope, prerequisites, refusal behavior and known limitations. For a complex 11-parameter comparison tool, an agent has everything needed to decide whether and how to call it.

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%, so the nine input channels (file object, URL, path, base64 for each revision) are already documented. The description adds only that text-based PDFs may come via upload or URL and that older revisions are often on web.archive.org; it does not clarify precedence when multiple input modes are supplied or mention path/base64 modes, so it stays at the high-coverage baseline.

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 and resource ('Compares two revisions' of MOSFET datasheets) and enumerates exactly which parameters it reports (VDS, ID, RDS(on), etc.) with page/table-row/quote provenance. It also carves out a clear boundary ('discrete Si and SiC MOSFETs only') that separates it from sibling tools like table_diff or supplier_compare.

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 a PCN or a new datasheet revision arrives...') and lists when-not via OUT_OF_SCOPE refusals for IGBTs, modules, diodes and gate drivers, plus a prerequisite ('Needs both revisions'). It does not name an alternative tool for cases it declines, so it falls just short of a 5.

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