Add sparklines

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

Annotations cover the safety profile (readOnly=false, destructive=false, openWorld=false) but say nothing about content replacement. The description explicitly discloses that existing sparklines in `range` are overwritten, which is a genuinely useful behavioral fact an agent would otherwise miss. It adds no other context such as permission needs 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?

Two tightly written sentences with the core action and placement rule front-loaded; every clause carries information (placement direction, column-match case, overwrite behavior). No filler.

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 with no output schema and 40% schema coverage, the description explains the key structural contract but leaves the rich `style` parameter and any failure/permission behavior undocumented. An agent can call it, but only with the schema as a crutch.

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?

With schema coverage at only 40%, the description carries extra weight and does clarify the crucial `range` vs `source` relationship (per-row, or per-column on column match). However `style` — a large nested object with many sub-options — is never mentioned in the description, and `path`/`sheet` are assumed. Partial compensation only.

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?

States a specific verb+resource (add sparklines) and nails down the placement semantics: one sparkline per row of `source`, or per column when the cells match the columns. The parenthetical '(Insert > Sparklines)' anchors it to the UI equivalent. It does not explicitly name the sibling `delete_sparklines`, so it falls just short of a 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 description says what happens (replaces existing sparklines there) but never states when to reach for this tool versus alternatives such as deleting first with `delete_sparklines`, nor any prerequisites like needing an existing sheet. Usage must be inferred entirely from the mechanics.

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