update_default_branch

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

Beyond the annotations (destructiveHint, openWorldHint), the description discloses side effects on clone/MR/CI defaults, permission requirements (project-maintainer), and expected returns (updated project or validation/permission error). This adds meaningful behavioral context that annotations alone do not provide.

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?

The description is two sentences, with the core purpose and alternative front-loaded. The second sentence packs multiple clauses (side effects, permissions, returns) into a single long sentence, but it remains efficient and contains no filler. Slight density prevents a 5.

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 two-parameter mutation tool with no output schema, the description covers all essential operational details: the action, the alternative tool, side effects, permission requirements, and expected outcomes. Nothing an agent needs to call it correctly is missing.

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?

The input schema describes both parameters with 100% coverage (project_id and default_branch). The description adds no parameter-specific detail beyond what the schema already states, so the baseline score of 3 is appropriate.

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 (change) and resource (the default branch of a project), and explicitly contrasts it with the sibling create_branch tool. This makes the tool's purpose unambiguous and easily distinguished from alternatives without consulting the schema.

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?

It explicitly instructs when to use this tool versus create_branch, and provides context about the operation's effect on project defaults. The guidance is direct and leaves no ambiguity about which sibling to select.

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