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

Goes well beyond the annotations (which only say readOnlyHint=false, destructiveHint=false): it discloses that creation is gated like a push, subject to rulesets, and triggers a secret scan of commits no other ref reaches, that CI/webhooks fire, and that the 'repo' scope is required. This is exactly the kind of side-effect and prerequisite disclosure a mutating tool needs.

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?

Six dense clauses with no filler, front-loaded with the operation and followed by side effects, auth scope, and return shape in descending order of importance. Every sentence carries information an agent can act on.

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?

No output schema exists, yet the description supplies the return shape ({ref, sha}), the auth scope, and the gating/CI side effects. For a 4-required-param mutation tool, nothing material 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?

Schema coverage is 50%: sha and branch are documented in-schema, owner and repo are not. The description reinforces that sha must be an existing commit and branch is a new short name, but adds nothing about owner/repo. Baseline 3 is appropriate given the partial schema coverage.

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+constraint: 'Create a new branch ref pointing at an existing sha', plus the equivalent REST endpoint. An agent can distinguish it from merjax_delete_branch or merjax_update_pr_branch without opening 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?

Usage is implied by the verb (create a branch), but there is no explicit when-to-use/when-not guidance and no routing against adjacent siblings such as merjax_create_pr or merjax_open_draft_pr, which may also produce branches. The agent must infer when a bare branch ref is the right call.

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