union_tables

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

The annotation readOnlyHint=true already signals safety. The description adds little behavioral context beyond the term 'union' itself; it does not explain how schema mismatches are handled, whether deduplication applies by default, or what the output structure looks like.

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 a single sentence that immediately states the action and object with no wasted words. It is highly concise and front-loaded.

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?

Given the tool's complexity (14 parameters, no output schema, no parameter descriptions), this one-sentence description is severely under-specified. It provides no information about input requirements, edge cases, or what a successful union produces.

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 0%, and the description provides no information about the 14 parameters (e.g., filepaths, select, limit, row_mode). It mentions 'multiple workbook files' only at a high level, failing to compensate for the complete lack of parameter documentation.

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 uses a specific verb ('union') and names the resource ('worksheet or table data across multiple workbook files'). It clearly conveys the core operation, but it does not explicitly distinguish itself from sibling tools like cross_workbook_lookup or bulk_filter_workbooks.

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 qualifier 'comparable' implies that the tool should be used when data across files shares a compatible schema, but it gives no explicit when-to-use or when-not-to-use guidance, nor does it name alternatives.

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