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

Annotations already declare readOnlyHint=false, destructiveHint=false, openWorldHint=false and idempotentHint=false, so the safety profile is covered structurally. The description adds that it operates on an existing sheet and returns the updated sheet, but given idempotentHint=false it omits the practically important consequence that retrying appends duplicate rows. Useful but not rich disclosure beyond the annotations.

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 short sentences, front-loaded with the primary use case and followed by the exclusion routing. Every sentence carries distinct information; no filler or restatement of the title.

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, the description need not explain return values, and the description does note that the updated sheet comes back. Use-case coverage and sibling routing are complete; the only material omission is a warning about duplicate rows on retry for a non-idempotent append.

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 (rows, sheet) are documented in the schema, so the baseline is 3. The description adds only that the sheet must already exist and that rows are being appended; it contributes no additional format or defaulting detail 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?

The description states a specific verb and resource ('append rows of data to one of their existing Xenition spreadsheets') and explicitly contrasts itself with the two nearest siblings, create_spreadsheet and query_spreadsheet. An agent can distinguish this from every other add_* sibling by the target artifact (spreadsheet rows).

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?

It gives explicit when-to-use ('user wants to append rows of data to an existing spreadsheet') plus two named when-not cases with the alternative tool to use instead. This is exactly the routing guidance an agent needs and leaves nothing to inference.

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