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

Annotations declare destructiveHint=true and idempotentHint=false, and the description substantiates exactly what is destroyed and how: removed columns lose 'their values,' existing rows keep their values, new columns are null until upserted, and a type change 'is checked against every existing row first.' That is rich mutation-effect context well beyond the annotation flags, and it is consistent with them.

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?

Four sentences, front-loaded with the core action and operation list, followed by constraint details. Every sentence carries behavioral information; only mild overlap with the title's 'Change a dataset's schema.'

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 destructive mutation tool with no output schema, the description covers operation scope, data-preservation behavior, and the key-immutability constraint. It does not mention permissions/authorization or what a successful change returns, but the core calling context is present.

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 all seven parameters (baseline 3). The description adds real semantic value on top: it names update_columns as the mechanism for fixing descriptions/types, explains that add_columns yields nulls for existing rows, and notes the pre-check on type changes.

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 (changes) and resource (dataset schema/metadata) and enumerates the concrete operations: add columns, remove columns, fix a column's description or type, change description or cadence. An agent can distinguish it from update_view, upsert_rows, and create_dataset without opening schemas.

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?

Gives a concrete usage trigger ('when you start storing a new category or scenario, update the column description that lists them') and an explicit alternative for an excluded case ('The key cannot be changed; create a new dataset for that'). It also implicitly routes value-filling to upsert_rows ('new columns are null until you upsert values'), though it never states when to prefer update_view or when not to use this tool.

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