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

Annotations already cover the non-read-only, non-destructive profile, and the description adds real behavior beyond them: the draft flag is forced rather than passed, and draft PRs skip mergeability checks. It omits required permissions and whether the created PR object or number is returned.

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?

Two sentences, front-loaded with the action and then the differentiator against the sibling. Nothing is padded or 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 6-parameter mutation tool with no annotation detail on side effects and no output schema, the description leaves the agent guessing about base_branch defaults and the return value. It is adequate to select the tool but not fully sufficient to call it confidently.

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 0% and the description compensates only by pointing at merjax_create_pr's payload. It never explains owner/repo/title/head_branch, the optional base_branch default, or that is_draft is absent from the schema precisely because it is forced.

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 names a specific verb and resource ("Open a draft pull request") and explicitly frames it against the sibling merjax_create_pr, noting the one behavioral difference (is_draft forced true). An agent can distinguish it from both merjax_create_pr and merjax_set_pr_draft without opening another 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 gives a concrete usage context ("AI-in-progress PRs that shouldn't run mergeability checks yet") and implies create_pr as the alternative for non-draft work. It does not, however, contrast with merjax_set_pr_draft, which also produces a draft state, leaving some sibling selection to inference.

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