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

Annotations already declare readOnlyHint=false, destructiveHint=false and idempotentHint=false; the description usefully adds that the old working copy stays in the tree, clarifying the branch is non-destructive. It does not say what the new branch is called, whether it becomes the active working copy, or what the caller gets back.

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 with the trigger condition first and the key behavioral consequence second; no filler. It is efficient, though arguably under-informative rather than merely concise.

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 non-idempotent mutation with no output schema, the description covers the safety-relevant fact that the source stays intact, but omits the outcome (what the branch looks like, its naming, whether it is switched to) and the undocumented version parameter. Adequate but with clear gaps.

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 coverage is only 50%: the formula parameter is documented in the schema, but version has no description anywhere. The description's phrase "from a past version" weakly implies the version param identifies the source version, but it never states the expected format (id vs. name vs. label), which is a real gap for a required parameter.

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 gives a concrete verb+resource: starting a new line of work from a past version, i.e., branching. However it never distinguishes this from near-neighbors like open_version, restore_deleted, or duplicate_formula, so the agent must infer the difference.

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?

"Use this when the user wants to start a new line of work from a past version" is an explicit trigger condition, which is more than most definitions provide. It offers no exclusions or named alternatives, so the agent cannot tell when NOT to branch versus opening or restoring.

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