write_cell

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 safety profile is covered. The description adds two useful facts beyond them: the return of the previous value and the supported formats, but it does not explain that the existing cell content is overwritten, nor how the claimed idempotency interacts with returning a different 'previous value' on repeated calls.

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?

Two short sentences with no filler; the operation and its scope are front-loaded and the return behavior follows immediately. Nothing is wasted.

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 a 4-parameter schema fully described and no output schema, the description is nearly sufficient: it names the operation, scope and return value. Minor gaps remain, such as error behavior for a missing sheet or non-existent workbook path, but nothing required to invoke the tool correctly is absent.

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 the schema already documents path, cell, sheet default and the '=' formula/null-clears semantics of value. The description's 'one value or formula' adds only a restatement of what the schema's value description covers, so the baseline 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 (write one value/formula to a cell) plus the file formats supported (.xlsx/.xlsm), which lets an agent distinguish it from the sibling write_range by the 'one value ... a cell' scope. It stops short of naming write_range explicitly, so the sibling differentiation is inferred rather than stated.

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?

Usage is implied by scope: single-cell writes versus the sibling write_range, and the format constraint rules out non-xlsx files. There is no explicit when-to-use/when-not-to-use statement, no mention of create_sheet/create_workbook ordering, and no note that the file must already exist.

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