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

The annotations already signal a mutating, non-idempotent, non-open-world operation, so the description does not need to restate that. It adds useful behavioral detail beyond the annotations: "Other sheets are kept" clarifies side effects on existing workbooks, and "Free: 500 rows per file" discloses a quota constraint. No contradiction with the annotations is present.

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 three short sentences with no filler. It front-loads the core action, then packs the most decision-relevant facts—format selection, modes, preservation of other sheets, and row quota—into compact follow-up statements.

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?

For a 5-parameter write tool with a rich schema and no output schema, the description provides the key operational context: supported formats, mode choices, non-destructive effect on other sheets, and file-size limits. It does not describe the return value or error behavior, but the schema covers parameter semantics sufficiently for an agent to invoke the tool correctly.

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%, with detailed explanations for path, rows, mode, sheet, and out_path. The description mostly summarizes the mode enum and format selection rather than adding new meaning, so the baseline of 3 is appropriate; it does not need to compensate for schema gaps.

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: "write rows to an xlsx, csv, tsv or json file." It also clarifies that the output format is chosen by the extension of out_path, which distinguishes it from sibling read/query/convert tools. The name and title align tightly with this described behavior.

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 description opens with "Call this tool to write rows," which gives a clear general context for when the tool applies. However, it does not name alternatives, state when not to use it, or explain how it differs from sibling tools like sheet_load, sheet_convert, or sheet_add_column. Usage is implied rather than explicit.

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