create_sheet

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

Annotations already declare readOnlyHint=false, destructiveHint=true, idempotentHint=true and openWorldHint=false, so the mutation and safety profile is covered structurally. The description only adds the format constraint (.xlsx/.xlsm), and says nothing about what happens on a duplicate sheet name, whether the file is rewritten, or error behavior.

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?

A single front-loaded sentence naming the action, the resource, and the target format. There is no filler and nothing is buried.

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 mutation tool whose annotations already carry the destructive/idempotent profile, the description is minimally viable, but it omits name-uniqueness behavior, failure modes, and any confirmation that the sheet is appended when index is null.

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%, so name, path, index (0 = first, defaults to last) and headers are all documented in the schema. The description adds no parameter meaning beyond that, so the baseline of 3 applies.

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 ('add a new sheet') and constrains the target to existing .xlsx/.xlsm workbooks, which implicitly separates it from create_workbook. It is clear without explicitly naming siblings, so 4 rather than 5.

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 word 'existing' implies this is for workbooks that already exist (versus create_workbook for new ones), but there is no explicit when-to-use statement, no exclusion, and no mention of required preconditions such as the file needing to exist.

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