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

Annotations already declare the safety profile (not read-only, not destructive, not idempotent, open-world), so the description's added value is the default source branch and the range of valid parents (branch/tag/commit). It omits failure behavior, such as what happens if the branch name already exists, which keeps it from a 5.

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 sentence with zero filler, front-loading the action and then the valid sources and default. Nothing redundant.

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 simple 3-parameter mutation with annotations covering safety and no output schema to explain, the description covers the essentials. It leaves the agent guessing about remote vs local branch creation and conflict behavior, which are the only notable 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 33% (only `repo` documented), so the description must compensate, and it does: it explains that the parent can be a branch, tag, or commit and defaults to main. `name` is left implicit as the new branch name and `from`'s exact format is unspecified, so not a 5.

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 and resource ('Create a branch') and clarifies the accepted parent types (branch, tag, commit) plus the default. It does not distinguish itself from neighboring gh_* tools (gh_commit, gh_pull_create, gh_repo_settings), so it stops 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 gives no when-to-use context, no prerequisites (e.g. write access to the repo, whether the source branch must already exist), and no pointer to any alternative tool. The only contextual hint is the 'default the main branch' fallback.

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