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

Annotations only declare readOnlyHint=false and destructiveHint=false, so the description carries real weight here and delivers: it states the authenticated-caller plus write-access requirement and the return shape {number, url}. It does not cover edge-case behavior such as what happens when the head branch does not exist or a PR already exists for that pair.

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?

Three short sentences, front-loaded with the action, then the parameter defaults, then the auth and return contract. Nothing is wasted, though the first two sentences partly duplicate the schema.

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 six-parameter mutation tool with no output schema, the description supplies the essentials: the auth/write prerequisite and the return payload. The main missing piece is the draft-PR distinction, which matters given the sibling tool set.

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 100%, so every parameter is already documented, and the description's notes about head_branch being required and base_branch defaulting are restatements of the schema rather than new semantics. Baseline 3 applies; no additional constraint such as branch-name format or cross-repo head syntax is added.

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: 'Open a new pull request.' An agent can distinguish it from read-oriented siblings like merjax_get_pr or merjax_list_prs. It stops short of differentiating itself from the close sibling merjax_open_draft_pr, which is the one case where an agent could pick the wrong tool.

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?

There is no explicit when-to-use guidance and no stated alternative. The presence of merjax_open_draft_pr in the sibling list makes the omitted distinction costly, since 'open a new pull request' could plausibly cover both. The write-access prerequisite is stated, but that is a precondition, not usage routing.

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